Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.3

Students can download 11th Business Maths Chapter 4 Trigonometry Ex 4.3 Questions and Answers, Notes, Samcheer Kalvi 11th Business Maths Guide Pdf helps you to revise the complete Tamilnadu State Board New Syllabus, helps students complete homework assignments and to score high marks in board exams.

Tamilnadu Samacheer Kalvi 11th Business Maths Solutions Chapter 4 Trigonometry Ex 4.3

Samacheer Kalvi 11th Business Maths Trigonometry Ex 4.3 Text Book Back Questions and Answers

Question 1.
Express each of the following as the sum or difference of sine or cosine:
(i) sin\(\frac{A}{8}\) sin\(\frac{3A}{8}\)
(ii) cos(60° + A) sin(120° + A)
(iii) cos\(\frac{7 A}{3}\) sin\(\frac{5 A}{3}\)
(iv) cos 7θ sin 3θ
Solution:
(i) sin\(\frac{A}{8}\) sin\(\frac{3A}{8}\)
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.3 1
[∵ 2 sin A sin B = cos(A – B) – cos(A + B)
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.3 2
[∵ cos(-θ) = cos θ]

(ii) cos(60° + A) sin(120° + A) = \(\frac{1}{2}\) [2 cos(60° + A) sin(120° + A)] [Multiply and divide by 2]
= \(\frac{1}{2}\) [sin((60° + A) + (120° + A))] – sin((60° + A) – (120° + A))]
[∵ 2 cos A sin B = sin(A + B) – sin(A – B)]
= \(\frac{1}{2}\) [sin(180° + 2A) – sin(60° + A – 120° – A)]
= \(\frac{1}{2}\) [(-sin 2A) – sin(-60°)]
= \(\frac{1}{2}\) [-sin 2A + sin 60°]
= \(\frac{1}{2}\) [-sin 2A + \(\frac{\sqrt{3}}{2}\)]

(iii) cos\(\frac{7 A}{3}\) sin\(\frac{5 A}{3}\)
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.3 3

(iv) cos 7θ sin 3θ = \(\frac{1}{2}\) [sin(7θ + 3θ) – sin(7θ – 3θ)]
= \(\frac{1}{2}\) (sin 10θ – sin 4θ)

Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.3

Question 2.
Express each of the following as the product of sine and cosine
(i) sin A + sin 2A
(ii) cos 2A + cos 4A
(iii) sin 6θ – sin 2θ
(iv) cos 2θ – cos θ
Solution:
(i) sin A + sin 2A = 2 sin(\(\frac{A+2 A}{2}\)) cos(\(\frac{A-2 A}{2}\))
[∵ sin C + sin D = sin(\(\frac{C+D}{2}\)) cos(\(\frac{C-D}{2}\))]
= 2 sin \(\frac{3A}{2}\) cos \(\frac{A}{2}\) [∵ cos(-θ) = cos θ]

(ii) cos 2A + cos 4A = 2 cos(\(\frac{2 \mathrm{A}+4 \mathrm{A}}{2}\)) cos(\(\frac{2 \mathrm{A}-4 \mathrm{A}}{2}\))
[∵ cos C + cos D = 2 cos(\(\frac{C+D}{2}\)) cos(\(\frac{C-D}{2}\))
= 2 cos(\(\frac{6 \mathrm{A}}{2}\)) cos(\(\frac{6 \mathrm{-2A}}{2}\))
= 2 cos(3A) cos (-A) [∵ cos(-θ) = cos θ]
= 2 cos 3A cos A

(iii) sin 6θ – sin 2θ = 2 cos(\(\frac{6 \theta+2 \theta}{2}\)) cos(\(\frac{6 \theta-2 \theta}{2}\))
[∵ sin C – sin D = 2 cos(\(\frac{C+D}{2}\)) sin(\(\frac{C-D}{2}\))
= 2 cos(\(\frac{8 \theta}{2}\)) sin(\(\frac{4 \theta}{2}\))
= 2 cos 4θ sin 2θ

(iv) cos 2θ – cos θ = -2 sin(\(\frac{2 \theta+\theta}{2}\)) sin(\(\frac{2 \theta-\theta}{2}\))
[∵ cos C – cos D = -2 sin(\(\frac{C+D}{2}\)) sin(\(\frac{C-D}{2}\))
= -2 sin(\(\frac{3 \theta}{2}\)) sin(\(\frac{\theta}{2}\))

Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.3

Question 3.
Prove that
(i) cos 20° cos 40° cos 80° = \(\frac{1}{8}\)
(ii) tan 20° tan 40° tan 80° = √3.
Solution:
(i) cos 20° cos 40° cos 80° = \(\left(\frac{2 \sin 20^{\circ}}{2 \sin 20^{\circ}}\right)\) cos 20° cos 40° cos 80°
[multiply and divide by 2 sin 20°]
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.3 4
(Multiply and divide by 2)
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.3 5
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.3 6
[∵ sin(180° – θ) = sin θ]

(ii) tan 20° tan 40° tan 80°
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.3 7
Consider sin 20° × sin 40° sin 80°
= sin 20° sin (60° – 20°) sin (60° + 20°)
= sin 20° [sin2 60° – sin2 20°]
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.3 8
cos 20° × cos 40° cos 80° = \(\frac{1}{8}\) [∵ from (i)] …… (2)
divide (1) by (2) we get, tan 20° tan 40° tan 80° = \(\frac{\frac{\sqrt{3}}{8}}{\frac{1}{8}}\) = √3

Question 4.
Prove that
(i) (cos α – cos β)2 + (sin α – sin β)2 = 4 \(\sin ^{2}\left(\frac{\alpha-\beta}{2}\right)\)
(ii) sin A sin(60° + A) sin(60° – A) = sin 3A
Solution:
(i) LHS = (cos α – cos β)2 + (sin α – sin β)2
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.3 9

(ii) LHS = 4 sin A sin (60° + A) . sin (60° – A)
= 4 sin A {sin (60° + A) . sin (60° – A)}
= 4 sin A {sin2 60° – sin2 A}
= 4 sin A {\(\frac{3}{4}\) – sin2 A}
= 3 sin A – 4 sin3 A
= sin 3A
= RHS

Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.3

Question 5.
Prove that
(i) sin (A – B) sin C + sin (B – C) sin A + sin(C – A) sin B = 0
(ii) \(2 \cos \frac{\pi}{13} \cos \frac{9 \pi}{13}+\cos \frac{3 \pi}{13}+\cos \frac{5 \pi}{13}=0\)
Solution:
Consider sin (A – B) sin C
= (sin A cos B – cos A sin B) sin C
= sin A cos B sin C – cos A sin B sin C …….. (1)
Similarly sin(B – C) sin A = sin B cos C sin A – cos B sin C sin A …….. (2)
[Replace A by B, B by C, C by A in (1)]
and sin(C – A) sin B [Replace A by B, B by C, C by A in (2)]
= sin C cos A sin B – cos C sin A sin B …….. (3)
Adding (1), (2) and (3) we get
sin (A – B) sin C + sin (B – C) sin A + sin(C – A) sin B = 0

(ii) \(2 \cos \frac{\pi}{13} \cos \frac{9 \pi}{13}+\cos \frac{3 \pi}{13}+\cos \frac{5 \pi}{13}=0\)
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.3 10
[∵ cos C + cos D = 2 cos(\(\frac{C+D}{2}\)) cos(\(\frac{C-D}{2}\))]
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.3 11
[∵ cos(-θ) = cos θ]
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.3 12
[take 2 cos \(\frac{\pi}{3}\) as commom)
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.3 13
Hence proved.

Question 6.
Prove that
(i) \(\frac{\cos 2 A-\cos 3 A}{\sin 2 A+\sin 3 A}=\tan \frac{A}{2}\)
(ii) \(\frac{\cos 7 \mathbf{A}+\cos 5 \mathbf{A}}{\sin 7 \mathbf{A}-\sin 5 \mathbf{A}}=\cot \mathbf{A}\)
Solution:
(i) \(\frac{\cos 2 A-\cos 3 A}{\sin 2 A+\sin 3 A}=\tan \frac{A}{2}\)
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.3 14

(ii) \(\frac{\cos 7 \mathbf{A}+\cos 5 \mathbf{A}}{\sin 7 \mathbf{A}-\sin 5 \mathbf{A}}=\cot \mathbf{A}\)
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.3 15
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.3 16
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.3 17
Hence proved.

Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.3

Question 7.
Prove that cos 20° cos 40° cos 60° cos 80° = \(\frac{3}{16}\).
Solution:
LHS = cos 20° cos 40° cos 60° cos 80°
= cos 20° cos 40° (\(\frac{1}{2}\)) cos 80° [∵ cos 60° = \(\frac{1}{2}\)]
= \(\frac{1}{2}\) (cos 20° cos 40° cos 80°)
= \(\frac{1}{2}\left(\frac{2 \sin 20^{\circ}}{2 \sin 20^{\circ}}\right)\) (cos 20° cos 40° cos 80°)
[multiply and divide by 2 sin 20°]
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.3 18
[multiply and divide by 2]
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.3 19
Hence Proved.

Question 8.
Evaluate:
(i) cos 20° + cos 100° + cos 140°
(ii) sin 50° – sin 70° + sin 10°
Solution:
(i) LHS = (cos 20° + cos 100°) + cos 140°
= 2 \(\cos \left(\frac{20^{\circ}+100^{\circ}}{2}\right) \cos \left(\frac{20^{\circ}-100^{\circ}}{2}\right)\) + cos 140°
[∵ cos C + cos D = 2 cos(\(\frac{C+D}{2}\)) cos(\(\frac{C-D}{2}\))]
= 2 cos 60° cos(-40°) + cos 140°
= 2 × \(\frac{1}{2}\) × cos(-40°) + cos(180° – 140°)
[∵ cos(-θ) = cos θ, cos 60° = \(\frac{1}{2}\)
= cos 40° – cos 40°
= 0
Hence Proved.

(ii) LHS = (sin 50° – sin 70°) + sin 10°
= 2 \(\cos \left(\frac{50^{\circ}+70^{\circ}}{2}\right) \sin \left(\frac{50^{\circ}-70^{\circ}}{2}\right)\) + sin 10°
[∵ sin C – sin D = 2 cos(\(\frac{C+D}{2}\)) sin(\(\frac{C-D}{2}\))]
= 2 cos 60° sin(-10°) + sin 10°
= 2 × \(\frac{1}{2}\) (-sin 10°) + sin 10° [∵ sin(-θ) = -sin θ]
= -sin 10° + sin 10°
= 0
= RHS

Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.3

Question 9.
If cos A + cos B = \(\frac{1}{2}\) and sin A + sin B = \(\frac{1}{4}\), prove that \(\tan \left(\frac{\mathbf{A}+\mathbf{B}}{2}\right)=\frac{\mathbf{1}}{2}\)
Solution:
Given that cos A + cos B = \(\frac{1}{2}\)
\(2 \cos \left(\frac{\mathrm{A}+\mathrm{B}}{2}\right) \cos \left(\frac{\mathrm{A}-\mathrm{B}}{2}\right)=\frac{1}{2}\) …….. (1)
Also given that sin A + sin B = \(\frac{1}{4}\)
\(2 \sin \left(\frac{\mathrm{A}+\mathrm{B}}{2}\right) \cos \left(\frac{\mathrm{A}-\mathrm{B}}{2}\right)=\frac{1}{4}\) ……. (2)
\(\frac{(2)}{(1)}\) gives
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.3 20

Question 10.
If sin(y + z – x), sin(z + x – y), sin(x + y – z) are in A.P, then prove that tan x, tan y and tan z are in A.P.
Solution:
In A.P. commom difference are equal, namely t2 – t1 = t3 – t2
sin(z + x – y) – sin(y + z – x) = sin(x + y – z) – sin(z + x – y)
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.3 21
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.3 22
cos z sin (x – y) = cos x sin (y – z)
cos z (sin x cos y – cos x sin y) = cos x (sin y cos z – cos y sin z)
Divide bothsides by cos x cos y cos z we get
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.3 23
tan x – tan y = tan y – tan z
Multiply both sides by (-1) we get,
tan y – tan x = tan z – tan y
This means tan x, tan y, and tan z are in A.P.
Hence proved.

Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.3

Question 11.
If cosec A + sec A = cosec B + sec B prove that cot(\(\frac{A+B}{2}\)) = tan A tan B.
Solution:
Given that cosec A + sec A = cosec B + sec B
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.3 24
Arrange T-ratios of the sine and cosine in the separate side
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.3 25
[∵ sin C – sin D = 2 cos(\(\frac{C+D}{2}\)) sin(\(\frac{C-D}{2}\))]
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.3 26
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.3 27

Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.2

Students can download 11th Business Maths Chapter 4 Trigonometry Ex 4.2 Questions and Answers, Notes, Samcheer Kalvi 11th Business Maths Guide Pdf helps you to revise the complete Tamilnadu State Board New Syllabus, helps students complete homework assignments and to score high marks in board exams.

Tamilnadu Samacheer Kalvi 11th Business Maths Solutions Chapter 4 Trigonometry Ex 4.2

Samacheer Kalvi 11th Business Maths Trigonometry Ex 4.2 Text Book Back Questions and Answers

Question 1.
Find the values of the following:
(i) cosec 15°
(ii) sin (-105°)
(iii) cot 75°
Solution:
(i) cosec 15° = \(\frac{1}{\sin 15^{\circ}}\)
Consider sin 15° = sin(45° – 30°)
= sin 45° cos 30° – cos 45° sin 30°
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.2 1
cosec 15° = \(\frac{1}{\sin 15^{\circ}}\) = \(\frac{2 \sqrt{2}}{\sqrt{3}-1}\)

(ii) sin (-105°) = -sin (105°) (∵ sin (-θ) = – sin θ)
= -[sin(60° + 45°)]
= -[sin 60° cos 45° + cos 60° sin 45°]
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.2 2

(iii) cot 75° = \(\frac{1}{\tan 75^{\circ}}\)
Consider tan 75° = tan (30° + 45°)
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.2 3
cot 75° = \(\frac{1}{\tan 75^{\circ}}=\frac{\sqrt{3}-1}{\sqrt{3}+1}\)

Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.2

Question 2.
Find the values of the following:
(i) sin 76° cos 16° – cos 76° sin 16°
(ii) \(\sin \frac{\pi}{4} \cos \frac{\pi}{12}+\cos \frac{\pi}{4} \sin \frac{\pi}{12}\)
(iii) cos 70° cos 10° – sin 70° sin 10°
(iv) cos2 15° – sin2 15°
Solution:
(i) Given that, sin 76° cos 16° – cos 76° sin 16° (∴ This is of the form sin(A – B))
= sin(76° – 16°)
= sin 60°
= \(\frac{\sqrt{3}}{2}\)

(ii) This is of the form sin(A + B) = \(\sin \left(\frac{\pi}{4}+\frac{\pi}{12}\right)\)
= \(\sin \left(\frac{3 \pi+\pi}{12}\right)\)
= \(\sin \frac{4 \pi}{12}\)
= \(\sin \frac{\pi}{3}\)
= \(\frac{\sqrt{3}}{2}\) (∵ sin 60° = \(\frac{\sqrt{3}}{2}\))

(iii) Given that cos 70° cos 10° – sin 70° sin 10°
(This is of the form of cos (A + B), A = 70°, B = 10°)
= cos (70° + 10°)
= cos 80°

(iv) cos2 15° – sin2 15°
[∵ cos 2A = cos2 A – sin2 A, Here A = 15°]
= cos (2 × 15°)
= cos 30°
= \(\frac{\sqrt{3}}{2}\)

Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.2

Question 3.
If sin A = \(\frac{3}{5}\), 0 < A < \(\frac{\pi}{2}\) and cos B = \(\frac{-12}{13}\), π < B < \(\frac{3 \pi}{2}\), find the values of the following:
(i) cos(A + B)
(ii) sin(A – B)
(iii) tan(A – B)
Solution:
Given that sin A = \(\frac{3}{5}\), 0 < A < \(\frac{\pi}{2}\) (i.e., A lies in first quadrant)
Since A lies in first quadrant cos A is positive.
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.2 4
cos A = \(\frac{\text { Adjacent side }}{\text { Hypotenuse }}=\frac{4}{5}\)
tan A = \(\frac{3}{4}\)
AB = \(\sqrt{5^{2}-3^{2}}\) = 4
Also given that cos B = \(\frac{-12}{13}\), π < B < \(\frac{3 \pi}{2}\) (i.e., B lies in third quadrant)
Now sin B lies in third quadrant. sin B is negative.
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.2 5
CA = \(\sqrt{13^{2}-12^{2}}\) = 5
sin B = \(\frac{-\text { Opposite side }}{\text { Hypotenuse }}=\frac{-5}{13}\)
tan B = \(\frac{-\text { Opposite side }}{\text { Adjacent }}=\frac{5}{12}\) [B lies in 3rd quadrant. tan B is positive.]
(i) cos(A + B) = cos A cos B – sin A sin B
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.2 6

(ii) sin(A – B) = sin A cos B – cos A sin B
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.2 7

(iii) tan(A – B)
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.2 8

Question 4.
If cos A = \(\frac{13}{14}\) and cos B = \(\frac{1}{7}\) where A, B are acute angles prove that A – B = \(\frac{\pi}{3}\)
Solution:
cos A = \(\frac{13}{14}\), cos B = \(\frac{1}{7}\)
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.2 9
cos(A – B) = cos A cos B + sin A sin B
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.2 33
cos(A – B) = cos 60°
A – B = 60° = \(\frac{\pi}{3}\)

Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.2

Question 5.
Prove that 2 tan 80° = tan 85° – tan 5°.
Solution:
Consider tan 80° = tan(85° – 5°)
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.2 10
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.2 11
∴ 2 tan 80° = tan 85° – tan 5°
Hence Proved.

Question 6.
If cot α = \(\frac{1}{2}\), sec β = \(\frac{-5}{3}\), where π < α < \(\frac{3 \pi}{2}\) and \(\frac{\pi}{2}\) < β < π, find the value of tan(α + β). State the quadrant in which α + β terminates.
Solution:
Given that cot α = \(\frac{1}{2}\) where π < α < \(\frac{3 \pi}{2}\) (i.e,. α lies in third quadrant)
tan α = \(\frac{1}{\frac{1}{2}}\) = 2 [∵ In 3rd quadrant tan α is positive]
Also given that sec β = \(\frac{-5}{3}\) where \(\frac{\pi}{2}\) < β < π (i.e., β lies in second quadrant cos β and tan β are negative)
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.2 12
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.2 13
tan (α + β) = \(\frac{2}{11}\) which is positive.
α + β terminates in first quandrant.

Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.2

Question 7.
If A + B = 45°, prove that (1 + tan A) (1 + tan B) = 2 and hence deduce the value of tan 22\(\frac{1}{2}\).
Solution:
Given A + B = 45°
tan (A + B) = tan 45°
\(\frac{\tan A+\tan B}{1-\tan A \tan B}=1\)
tan A + tan B = 1 – tan A . tan B
tan A + tan B + tan A tan B = 1
Add 1 on both sides we get,
(1 + tan A) + tan B + tan A tan B = 2
1(1+ tan A) + tan B (1 + tan A) = 2
(1 + tan A) (1 + tan B) = 2 ……. (1)
Put A = B = 22\(\frac{1}{2}\) in (1) we get
(1 + tan 22\(\frac{1}{2}\)) (1 + tan 22\(\frac{1}{2}\)) = 2
⇒ (1 + tan22\(\frac{1}{2}\))2 = 2
⇒ 1 + tan 22\(\frac{1}{2}\) = ±√2
⇒ tan 22\(\frac{1}{2}\) = ±√2 – 1
Since 22\(\frac{1}{2}\) is acute, tan 22\(\frac{1}{2}\) is positive and therefore tan 22\(\frac{1}{2}\) = √2 – 1

Question 8.
Prove that
(i) sin(A + 60°) + sin(A – 60°) = sin A.
(ii) tan 4A tan 3A tan A + tan 3A + tan A – tan 4A = 0
Solution:
(i) LHS = sin (A + 60°) + sin (A – 60°)
= sin A cos 60° + cos A sin 60° + sin A cos 60° – cos A sin 60°
= 2 sin A cos 60°
= 2 sin A \(\left(\frac{1}{2}\right)\)
= sin A
= RHS

(ii) 4A = 3A + A
tan 4A = tan (3A + A)
tan 4A = \(\frac{\tan 3 \mathrm{A}+\tan \mathrm{A}}{1-\tan 3 \mathrm{A} \tan \mathrm{A}}\)
on cross multiplication we get,
tan 3A + tan A = tan 4A (1 – tan 3A tan A) = tan 4A – tan 4A tan 3A tanA
i.e., tan 4A tan 3A tan A + tan 3A + tan A = tan 4A
(or) tan 4A tan 3A tan A + tan 3A + tan A – tan 4A = 0

Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.2

Question 9.
(i) If tan θ = 3 find tan 3θ
(ii) If sin A = \(\frac{12}{13}\), find sin 3A.
Solution:
(i) tan θ = 3
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.2 14

(ii) If sin A = \(\frac{12}{13}\)
We know that sin 3A = 3 sin A – 4 sin3 A
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.2 15

Question 10.
If sin A = \(\frac{3}{5}\), find the values of cos 3A and tan 3A.
Solution:
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.2 16
Given sin A = \(\frac{3}{5}\)
cos A = \(\frac{\text { Adjacent side }}{\text { Hypotenuse }}=\frac{4}{5}\)
and tan A = \(\frac{\text { Opposite side }}{\text { Adjacent side }}=\frac{3}{4}\)
We know that cos 3A = 4 cos3 A – 3 cos A
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.2 17

Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.2

Question 11.
Prove that \(\frac{\sin (B-C)}{\cos B \cos C}+\frac{\sin (C-A)}{\cos C \cos A}+\frac{\sin (A-B)}{\cos A \cos B}=0\)
Solution:
Consider \(\frac{\sin (B-C)}{\cos B \cos C}\)
= \(\frac{\sin \mathrm{B} \cos \mathrm{C}-\cos \mathrm{B} \sin \mathrm{C}}{\cos \mathrm{B} \cos \mathrm{C}}\)
= \(\frac{\sin B \cos C}{\cos B \cos C}-\frac{\cos B \sin C}{\cos B \cos C}\)
= tan B – tan C ……… (1)
Similarly we can prove \(\frac{\sin (C-A)}{\cos C \cos A}\) = tan C – tan A …….(2)
and \(\frac{\sin (A-B)}{\cos A \cos B}\) = tan A – tan B …….. (3)
Add (1), (2) and (3) we get
\(\frac{\sin (B-C)}{\cos B \cos C}+\frac{\sin (C-A)}{\cos C \cos A}+\frac{\sin (A-B)}{\cos A \cos B}=0\)

Question 12.
If tan A – tan B = x and cot B – cot A = y prove that cot(A – B) = \(\frac{1}{x}+\frac{1}{y}\).
Solution:
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.2 18
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.2 19
Hence proved.

Question 13.
If sin α + sin β = a and cos α + cos β = b, then prove that cos(α – β) = \(\frac{a^{2}+b^{2}-2}{2}\)
Solution:
Consider a2 + b2 = sin2α + sin2β + 2 sin α sin β + cos2α + cos2β + 2 cos α cos β
a2 + b2 = (sin2α + cos2α) + (sin2β + cos2β) + 2[cos α cos β + sin α sin β]
a2 + b2 = 1 + 1 + 2 cos(α – β)
∴ cos(α – β) = \(\frac{a^{2}+b^{2}-2}{2}\)

Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.2

Question 14.
Find the value of tan\(\frac{\pi}{8}\).
Solution:
Method 1:
\(\frac{\pi}{8}=\frac{180^{\circ}}{8}=\frac{45^{\circ}}{2}=22 \frac{1}{2}\)
We know that tan 2A = \(\frac{2 \tan A}{1-\tan ^{2} A}\)
Put A = 22\(\frac{1}{2}\) in the above formula
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.2 20
On cross multiplication we get
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.2 21
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.2 22
Here a = 1, b = 2, c = -1
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.2 23
Since 22\(\frac{1}{2}\) is acute tan 22\(\frac{1}{2}\) is positive tan 22\(\frac{1}{2}\) = tan \(\frac{\pi}{8}\)
= -1 + √2
= √2 – 1

Method 2:
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.2 24
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.2 25
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.2 26
∴ \(\tan ^{2} 22 \frac{1}{2}=(\sqrt{2}-1)^{2}\)
Taking square root, \(\tan ^{2} 22 \frac{1}{2}\) = ±(√2 – 1)
But \(22 \frac{1}{2}\) lies in first quadrant, tan \(22 \frac{1}{2}\) is positive.
∴ tan 22\(\frac{1}{2}\) = √2 – 1

Method 3:
consider tan A = \(\frac{\sin 2 A}{1+\cos 2 A}\)
Put A = \(22 \frac{1}{2}\)
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.2 27
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.2 28
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.2 29
tan 22\(\frac{1}{2}\) = √2 – 1

Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.2

Question 15.
If tan α = \(\frac{1}{7}\), sin β = \(\frac{1}{\sqrt{10}}\). Prove that α + 2β = \(\frac{\pi}{4}\) where 0 < α < \(\frac{\pi}{2}\) and 0 < β < \(\frac{\pi}{2}\).
Solution:
Given that tan α = \(\frac{1}{7}\)
We wish to find tan(α + 2β)
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.2 30
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.2 31
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.2 32

11th Model Question Papers 2020-2021 Tamil Nadu State Board English Tamil Medium with Answers

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11th New Public Exam Model Question Papers Tamil Nadu 2020 2021 English Tamil Medium

11th New Model Question Papers 2020 2021 Tamil Nadu

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Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.1

Students can download 11th Business Maths Chapter 4 Trigonometry Ex 4.1 Questions and Answers, Notes, Samcheer Kalvi 11th Business Maths Guide Pdf helps you to revise the complete Tamilnadu State Board New Syllabus, helps students complete homework assignments and to score high marks in board exams.

Tamilnadu Samacheer Kalvi 11th Business Maths Solutions Chapter 4 Trigonometry Ex 4.1

Samacheer Kalvi 11th Business Maths Trigonometry Ex 4.1 Text Book Back Questions and Answers

Question 1.
Convert the following degree measure into radian measure
(i) 60°
(ii) 150°
(iii) 240°
(iv) -320°
Solutions:
(i) 1°= \(\frac{\pi}{180}\) radians
∴ 60° = \(\frac{\pi}{180}\) × 60 radians = \(\frac{\pi}{3}\) radians.

(ii) 150° = \(\frac{\pi}{180}\) × 150 radians = \(\frac{5 \pi}{6}\) radians.

(iii) 240° = \(\frac{\pi}{180}\) × 240 radians = \(\frac{4 \pi}{3}\) radians.

(iv) -320° = \(\frac{\pi}{180}\) × -320 = \(\frac{-16 \pi}{9}\) radians

Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.1

Question 2.
Find the degree measure corresponding to the following radian measure.
(i) \(\frac{\pi}{8}\)
(ii) \(\frac{9 \pi}{5}\)
(iii) -3
(iv) \(\frac{11 \pi}{18}\)
Solution:
We know that, one radian = \(\frac{180^{\circ}}{\pi}\)
(i) \(\frac{\pi}{8}\)
\(\frac{\pi}{8}=\frac{180^{\circ}}{\pi} \times \frac{\pi}{8}\) degrees
= \(\frac{45}{2}\)
= 22.5°
= 22°30′ [∵ 0.5° = (0.5 × 60)’ = 30′]

(ii) \(\frac{9 \pi}{5}\)
\(\frac{9 \pi}{5}=\frac{180^{\circ}}{\pi} \times \frac{9 \pi}{5}\) degrees
= 36 × 9 degrees
= 324°

(iii) -3
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.1 Q2
= -171.81°
= -171°48′ (∵ 0.8° = (0.8 × 60)’ = 48′)

(iv) \(\frac{11 \pi}{18}\)
\(\frac{11 \pi}{18}=\frac{180}{\pi} \times \frac{11 \pi}{18}\)
= 10 × 11°
= 110°

Question 3.
Determine the quadrants in which the following degree lie.
(i) 380°
(ii) -140°
(iii) 1195°
Solution:
(i) 380° = 360°+ 20°
This is of the form 360° + θ
∴ After one completion of the round, the angle is 20°, 380° lies in the I quadrant.
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.1 Q3

(ii) -140° = -90° + (-50°)
The angle is negative it moves in the anti-clockwise direction.
-140° lies in the III quadrants.
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.1 Q3.1

(iii) 1195° = (3 × 360°) + 90° + 25°
∴ After three completion round, the angle will lie in the II quadrant.
1195° lies in the II quadrant.
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.1 Q3.2

Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.1

Question 4.
Find the values of each of the following trigonometric ratios.
(i) sin 300°
(ii) cos(-210°)
(iii) sec 390°
(iv) tan(-855°)
(v) cosec 1125°
Solution:
(i) sin 300° = sin(360° – 60°)
[For 360° – 60°. No change in T-ratio. 300° lies in 4th quadrant ‘sin’ is negative]
= -sin 60°
= \(-\frac{\sqrt{3}}{2}\)

(ii) cos(-210°) = cos 210° (∵ cos(-θ) = cos θ)
[∵ 180 + 30°. No change in T-ratio. 210° lies 3rd quadrant ‘cos’ is negative]
= cos(180° + 30°)
= -cos 30°
= \(-\frac{\sqrt{3}}{2}\)

(iii) sec 390° = sec(360° + 30°)
= sec 30°
= \(\frac{1}{\cos 30^{\circ}}\)
= \(\frac{1}{\left(\frac{\sqrt{3}}{2}\right)}\)
= \(\frac{2}{\sqrt{3}}\)

(iv) tan(-855°) = -tan 855° (∵ tan(-θ) = – tan θ)
[∵ Multiplies of 360° are dropped out. For 180° – 45°. No change in T-ratio. 180° – 45° lies in 2nd quadrant ‘tan’ is negative]
= -tan(2 × 360° + 135°)
= -tan 135°
= -tan(180° – 45°)
= -(-tan 45°)
= -(-1)
= 1

(v) cosec 1125° = cosec(3 × 360°+ 45°)
= cosec 45°
= \(\frac{1}{\sin 45^{\circ}}\)
= \(\frac{1}{\left(\frac{1}{\sqrt{2}}\right)}\)
= √2

Question 5.
Prove that:
(i) tan(-225°) cot(-405°) – tan(-765°) cot(675°) = 0.
(ii) 2 sin2 \(\frac{\pi}{6}\) + cosec2 \(\frac{7 \pi}{6}\) cos2 \(\frac{\pi}{3}\) = \(\frac{3}{2}\)
(iii) \(\sec \left(\frac{3 \pi}{2}-\theta\right) \sec \left(\theta-\frac{5 \pi}{2}\right)+\tan \left(\frac{5 \pi}{2}+\theta\right) \tan \left(\theta-\frac{5 \pi}{2}\right)=-1\)
Solution:
(i) tan(-225°) = -(tan 225°)
= -(tan(180° + 45°))
= – tan 45°
= – 1
cot(-405°) = -(cot 405°)
= – cot(360° + 45°) [∵ For 360° + 45° no change in T-ratio.]
= -cot 45°
= -1
tan(-765°) = -tan 765°
= -tan(2 × 360° + 45°)
= -tan 45°
= -1
cot 675° = cot (360°+ 315°)
= cot 315°
= cot(360° – 45°)
= -cot 45°
= -1
LHS = tan(-225°) cot(-405°) – tan(-765°) cot(675°)
= (-1) (-1) – (-1) (-1)
= 1 – 1
= 0
= RHS.
Hence proved.

(ii) 2 sin2 \(\frac{\pi}{6}\) + cosec2 \(\frac{7 \pi}{6}\) cos2 \(\frac{\pi}{3}\) = \(\frac{3}{2}\)
LHS = 2 sin2 \(\frac{\pi}{6}\) + cosec2 \(\frac{7 \pi}{6}\) cos2 \(\frac{\pi}{3}\)
[∵ \(\frac{7 \pi}{6}\) = 210°, 210° = 180° + 30°. For 180° + 30° no change in T-ratio.
210° lies in 3rd quadrant, cosec θ is negative.]
= 2\(\left(\sin \frac{\pi}{6}\right)^{2}\) + (cosec (180° + 30°))2 \(\left(\cos \frac{\pi}{3}\right)^{2}\)
= 2 \(\left(\frac{1}{2}\right)^{2}\) + (-cosec 30°)2 . \(\left(\frac{1}{2}\right)^{2}\)
= \(2 \times \frac{1}{4}+(-2)^{2} \frac{1}{4}\)
= \(\frac{2}{4}+\frac{4}{4}=\frac{6}{4}\)
= \(\frac{6}{4}\)
= \(\frac{3}{2}\)
= RHS

(iii) sec(\(\frac{3 \pi}{2}\) – θ) = sec (270° – θ) = -cosec θ
[∵ For 270° – θ change T-ratio. So add ‘co’ infront ‘sec’, it becomes ‘cosec’]
sec(θ – \(\frac{5 \pi}{2}\)) = \(\sec \left(-\left(\frac{5 \pi}{2}-\theta\right)\right)\)
= sec(\(\frac{5 \pi}{2}\) – θ) [∵ sec(-θ) = θ]
= sec(450° – θ)
= sec (360° + (90° – θ))
= sec (90° – θ)
= cosec θ
[∵ For 90° – θ change in T-ratio. So add ‘co’ in front of ‘sec’ it becomes ‘cosec’]
tan(\(\frac{5 \pi}{2}\) + θ) = tan(450° + θ)
[∵ For 90° + θ, change in T-ratio. So add ‘co’ in front of ‘tan’ it becomes ‘cot’]
= tan (360° + (90° + θ))
= tan (90° + θ)
= -cot θ
\(\tan \left(\theta-\frac{5 \pi}{2}\right)=\tan \left(-\left(\frac{5 \pi}{2}-\theta\right)\right)\)
= \(-\tan \left(\frac{5 \pi}{2}-\theta\right)\) [∵ tan(-θ) = -tan θ]
= -tan(450° – θ)
= -tan(360° + (90° – θ))
= -tan(90° – θ)
= -cot θ
LHS = \(\sec \left(\frac{3 \pi}{2}-\theta\right) \sec \left(\theta-\frac{5 \pi}{2}\right)+\tan \left(\frac{5 \pi}{2}+\theta\right) \tan \left(\theta-\frac{5 \pi}{2}\right)\)
= -cosec θ (cosec θ) + (-cot θ) (-cot θ)
= -cosec2 θ + cot2 θ
= -(1 + cot2 θ) + cot2 θ [∵ 1 + cot2 θ = cosec2 θ]
= -1
= RHS

Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.1

Question 6.
If A, B, C, D are angles of a cyclic quadrilateral, prove that: cos A + cos B + cos C + cos D = 0.
Solution:
Note: If the vertices of a quadrilateral lie on the circle then the quadrilateral is called a cyclic quadrilateral.
In a cyclic quadrilateral sum of opposite angles are 180°.
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.1 Q6
Since A, B, C, D are angles of cyclic quadrilateral
A + C = 180° and B + D = 180°
LHS = cos A + cos B + cos C + cos D
= cos A + cos B + cos(180° – A) + cos(180° – B)
= cos A + cos B – cos A – cos B
= 0
= RHS

Question 7.
Prove that
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.1 Q7.2
(ii) sin θ . cos{sin(\(\frac{\pi}{2}\) – θ) . cosec θ + cos(\(\frac{\pi}{2}\) – θ) . sec θ} = 1
Solution:
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.1 Q7.2
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.1 Q7

(ii) sin θ . cos{sin(\(\frac{\pi}{2}\) – θ) . cosec θ + cos(\(\frac{\pi}{2}\) – θ) . sec θ} = 1
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.1 Q7.1

Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.1

Question 8.
Prove that: cos 510° cos 330° + sin 390° cos 120° = -1.
Solution:
LHS = cos 510° cos 330° + sin 390° cos 120°
= cos(360° + 150°) cos(360° – 30°) + sin(360° + 30°) × cos(180° – 60°)
= cos 150° cos 30° + sin 30° (-cos 60°)
= cos(180° – 30°) cos 30° + sin 30° cos 60°
= -cos 30° cos 30° + \(\frac{1}{2} \times\left(\frac{-1}{2}\right)\)
= \(-\frac{\sqrt{3}}{2} \times \frac{\sqrt{3}}{2}-\frac{1}{2} \times \frac{1}{2}\)
= \(-\frac{3}{4}-\frac{1}{4}\)
= \(\frac{-3-1}{4}\)
= -1

Question 9.
Prove that:
(i) tan(π + x) cot(x – π) – cos(2π – x) cos(2π + x) = sin2 x.
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.1 Q9.1
Solution:
(i) tan(π + x) cot(x – π) – cos(2π – x) cos(2π + x) = (tan x) (-cot(π – x) – cos x cos x
[∵ cot(x – π) = cot(-(π – x)) = -cot(π – x) = cot x]
= tan x cot x – cos2 x
= 1 – cos2 x
= sin2 x [∵ sin2 x + cos2 x = 1 ⇒ sin2 x = (1 – cos2 x)]

Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.1 Q9.1
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.1 Q9

Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.1

Question 10.
If sin θ = \(\frac{3}{5}\), tan φ = \(\frac{1}{2}\) and \(\frac{\pi}{2}\) < θ < π < φ < \(\frac{3 \pi}{2}\), then find the value of 8 tan θ – √5 sec φ.
Solution:
Samacheer Kalvi 11th Business Maths Guide Chapter 4 Trigonometry Ex 4.1 Q10
Given that sin θ = \(\frac{3}{5}=\frac{\text { Opposite side }}{\text { Hypotenuse }}\)
∵ AB = \(\sqrt{5^{2}-3^{2}}=\sqrt{25-9}=\sqrt{16}\) = 4
Here θ lies in second quadrant [∵ \(\frac{\pi}{2}\) < θ < π]
∵ tan θ is negative.
tan θ = \(-\frac{3}{4}\)
Also given that tan Φ = \(\frac{1}{2}=\frac{\text { Opposite side }}{\text { Adjacent side }}\)
∴ PR = \(\sqrt{\mathrm{PQ}^{2}+\mathrm{QP}^{2}}=\sqrt{4+1}=\sqrt{5}\)
Here Φ lies in third quadrant (∵ π < Φ < \(\frac{3 \pi}{2}\))
∴ sec Φ is negative.
\(\sec \phi=\frac{1}{\cos \phi}=-\frac{1}{\left(\frac{2}{\sqrt{5}}\right)}=-\frac{\sqrt{5}}{2}\)
Now 8 tan θ – √5 sec Φ = \(8\left(-\frac{3}{4}\right)-\sqrt{5}\left(\frac{-\sqrt{5}}{2}\right)\)
= 2 × (-3) + \(\frac{5}{2}\)
= -6 + \(\frac{5}{2}\)
= \(\frac{-12+5}{2}\)
= \(\frac{-7}{2}\)

Samacheer Kalvi 11th Business Maths Guide Chapter 3 Analytical Geometry Ex 3.7

Students can download 11th Business Maths Chapter 3 Analytical Geometry Ex 3.7 Questions and Answers, Notes, Samcheer Kalvi 11th Business Maths Guide Pdf helps you to revise the complete Tamilnadu State Board New Syllabus, helps students complete homework assignments and to score high marks in board exams.

Tamilnadu Samacheer Kalvi 11th Business Maths Solutions Chapter 3 Analytical Geometry Ex 3.7

Samacheer Kalvi 11th Business Maths Analytical Geometry Ex 3.7 Text Book Back Questions and Answers

Question 1.
If m1 and m2 are the slopes of the pair of lines given by ax2 + 2hxy + by2 = 0, then the value of m1 + m2 is:
(a) \(\frac{2 h}{b}\)
(b) \(-\frac{2 h}{b}\)
(c) \(\frac{2 h}{a}\)
(d) \(-\frac{2 h}{a}\)
Answer:
(b) \(-\frac{2 h}{b}\)

Question 2.
The angle between the pair of straight lines x2 – 7xy + 4y2 = 0 is:
(a) \(\tan ^{-1}\left(\frac{1}{3}\right)\)
(b) \(\tan ^{-1}\left(\frac{1}{2}\right)\)
(c) \(\tan ^{-1}\left(\frac{\sqrt{33}}{5}\right)\)
(d) \(\tan ^{-1}\left(\frac{5}{\sqrt{33}}\right)\)
Answer:
(c) \(\tan ^{-1}\left(\frac{\sqrt{33}}{5}\right)\)
Hint:
x2 – 7xy + 4y2 = 0
Here 2h = -7, a = 1, b = 4
Samacheer Kalvi 11th Business Maths Guide Chapter 3 Analytical Geometry Ex 3.7 Q2

Samacheer Kalvi 11th Business Maths Guide Chapter 3 Analytical Geometry Ex 3.7

Question 3.
If the lines 2x – 3y – 5 = 0 and 3x – 4y – 7 = 0 are the diameters of a circle, then its centre is:
(a) (-1, 1)
(b) (1, 1)
(c) ( 1, -1)
(d) (-1, -1)
Answer:
(c) ( 1, -1)
Hint:
To get centre we must solve the given equations
2x – 3y – 5 = 0 …….(1)
3x – 4y – 7 = 0 ………(2)
(1) × 3 ⇒ 6x – 9y = 15
(2) × 2 ⇒ 6x – 8y = 14
Subtracting, -y = 1 ⇒ y = -1
Using y = -1 in (1) we get
2x + 3 – 5 = 0
⇒ 2x = 2
⇒ x = 1

Question 4.
The x-intercept of the straight line 3x + 2y – 1 = 0 is
(a) 3
(b) 2
(c) \(\frac{1}{3}\)
(d) \(\frac{1}{2}\)
Answer:
(c) \(\frac{1}{3}\)
Hint:
To get x-intercept put y = 0 in 3x + 2y – 1 = 0 we get
3x – 1 = 0
x = \(\frac{1}{3}\)

Samacheer Kalvi 11th Business Maths Guide Chapter 3 Analytical Geometry Ex 3.7

Question 5.
The slope of the line 7x + 5y – 8 = 0 is:
(a) \(\frac{7}{5}\)
(b) \(-\frac{7}{5}\)
(c) \(\frac{5}{7}\)
(d) \(-\frac{5}{7}\)
Answer:
(b) \(-\frac{7}{5}\)
Hint:
Slope of 7x + 5y – 8 = 0 is = \(\frac{-x \text { coefficient }}{y \text { coefficient }}\) = \(-\frac{7}{5}\)

Question 6.
The locus of the point P which moves such that P is at equidistance from their coordinate axes is:
(a) y = \(\frac{1}{x}\)
(b) y = -x
(c) y = x
(d) y = \(\frac{-1}{x}\)
Answer:
(c) y = x
Hint:
Samacheer Kalvi 11th Business Maths Guide Chapter 3 Analytical Geometry Ex 3.7 Q6
Given PA = PB
y1 = x1
∴ Locus is y = x

Samacheer Kalvi 11th Business Maths Guide Chapter 3 Analytical Geometry Ex 3.7

Question 7.
The locus of the point P which moves such that P is always at equidistance from the line x + 2y + 7 = 0:
(a) x + 2y + 2 = 0
(b) x – 2y + 1 = 0
(c) 2x – y + 2 = 0
(d) 3x + y + 1 = 0
Answer:
(a) x + 2y + 2 = 0
Hint:
Locus is line parallel to line x + 2y + 7 = 0 which is x + 2y + 2 = 0

Question 8.
If kx2 + 3xy – 2y2 = 0 represent a pair of lines which are perpendicular then k is equal to:
(a) \(\frac{1}{2}\)
(b) \(-\frac{1}{2}\)
(c) 2
(d) -2
Answer:
(c) 2
Hint:
Here a = k, b = -2
Condition for perpendicular is
a + b = 0
⇒ k – 2 = 0
⇒ k = 2

Samacheer Kalvi 11th Business Maths Guide Chapter 3 Analytical Geometry Ex 3.7

Question 9.
(1, -2) is the centre of the circle x2 + y2 + ax + by – 4 = 0, then its radius:
(a) 3
(b) 2
(c) 4
(d) 1
Answer:
(a) 3
Hint:
Given centre (-g, -f) = (1, -2)
From the given equation c = -4
Radius = \(\sqrt{g^{2}+f^{2}-c}=\sqrt{1+4-(-4)}=\sqrt{9}\) = 3

Question 10.
The length of the tangent from (4, 5) to the circle x2 + y2 = 16 is:
(a) 4
(b) 5
(c) 16
(d) 25
Answer:
(b) 5
Hint:
Length of the tangent from (x1, y1) to the circle x2 + y2 = 16 is \(\sqrt{x_{1}^{2}+y_{1}^{2}-16}=5\)

Samacheer Kalvi 11th Business Maths Guide Chapter 3 Analytical Geometry Ex 3.7

Question 11.
The focus of the parabola x2 = 16y is:
(a) (4 , 0)
(b) (-4, 0)
(c) (0, 4)
(d) (0, -4)
Answer:
(c) (0, 4)
Hint:
x2 = 16y
Here 4a = 16 ⇒ a = 4
Focus is (0, a) = (0, 4)

Question 12.
Length of the latus rectum of the parabola y2 = -25x:
(a) 25
(b) -5
(c) 5
(d) -25
Answer:
(a) 25
Hint:
y2 = -25a
Here 4a = 25 which is the length of the latus rectum.

Samacheer Kalvi 11th Business Maths Guide Chapter 3 Analytical Geometry Ex 3.7

Question 13.
The centre of the circle x2 + y2 – 2x + 2y – 9 = 0 is:
(a) (1, 1)
(b) (-1, 1)
(c) (-1, 1)
(d) (1, -1)
Answer:
(d) (1, -1)
Hint:
2g = -2, 2f = 2
g = -1, f = 1
Centre = (-g, -f) = (1, -1)

Question 14.
The equation of the circle with centre on the x axis and passing through the origin is:
(a) x2 – 2ax + y2 = 0
(b) y2 – 2ay + x2 = 0
(c) x2 + y2 = a2
(d) x2 – 2ay + y2 = 0
Answer:
(a) x2 – 2ax + y2 = 0
Hint:
Let the centre on the x-axis as (a, 0).
This circle passing through the origin so the radius
Samacheer Kalvi 11th Business Maths Guide Chapter 3 Analytical Geometry Ex 3.7 Q14
Now centre (h, k) = (a, 0)
Radius = a
Equation of the circle is (x – a)2 + (y – 0)2 = a2
⇒ x2 – 2ax + a2 + y2 = a2
⇒ x2 – 2ax + y2 = 0

Samacheer Kalvi 11th Business Maths Guide Chapter 3 Analytical Geometry Ex 3.7

Question 15.
If the centre of the circle is (-a, -b) and radius is \(\sqrt{a^{2}-b^{2}}\) then the equation of circle is:
(a) x2 + y2 + 2ax + 2by + 2b2 = 0
(b) x2 + y2 + 2ax + 2by – 2b2 = 0
(c) x2 + y2 – 2ax – 2by – 2b2 = 0
(d) x2 + y2 – 2ax – 2by + 2b2 = 0
Answer:
(a) x2 + y2 + 2ax + 2by + 2b2 = 0
Hint:
Equation of the circle is (x – h)2 + (y – k)2 = r2
⇒ (x + a)2 + (y + b)2 = a2 – b2
⇒ x2 + y2 + 2ax + 2by + a2 + b2 = a2 – b2
⇒ x2 + y2 + 2ax + 2by + 2b2 = 0

Question 16.
Combined equation of co-ordinate axes is:
(a) x2 – y2 = 0
(b) x2 + y2 = 0
(c) xy = c
(d) xy = 0
Answer:
(d) xy = 0
Hint:
Equation of x-axis is y = 0
Equation of y-axis is x = 0
Combine equation is xy = 0

Samacheer Kalvi 11th Business Maths Guide Chapter 3 Analytical Geometry Ex 3.7

Question 17.
ax2 + 4xy + 2y2 = 0 represents a pair of parallel lines then ‘a’ is:
(a) 2
(b) -2
(c) 4
(d) -4
Answer:
(a) 2
Hint:
Here a = 0, h = 2, b = 2
Condition for pair of parallel lines is b2 – ab = 0
4 – a(2) = 0
⇒ -2a = -4
⇒ a = 2

Question 18.
In the equation of the circle x2 + y2 = 16 then v intercept is (are):
(a) 4
(b) 16
(c) ±4
(d) ±16
Answer:
(c) ±4
Hint:
To get y-intercept put x = 0 in the circle equation we get
0 + y2 = 16
∴ y = ±4

Samacheer Kalvi 11th Business Maths Guide Chapter 3 Analytical Geometry Ex 3.7

Question 19.
If the perimeter of the circle is 8π units and centre is (2, 2) then the equation of the circle is:
(a) (x – 2)2 + (y – 2)2 = 4
(b) (x – 2)2 + (y – 2)2 = 16
(c) (x – 4)2 + (y – 4)2 = 16
(d) x2 + y2 = 4
Answer:
(c) (x – 2)2 + (y – 2)2 = 16
Hint:
Perimeter, 2πr = 8π
r = 4
Centre is (2, 2)
Equation of the circle is (x – 2)2 + (y – 2)2 = 42 = 16

Question 20.
The equation of the circle with centre (3, -4) and touches the x-axis is:
(a) (x – 3)2 + (y – 4)2 = 4
(b) (x – 3)2 + (y + 4)2 = 16
(c) (x – 3)2 + (y – 4)2 = 16
(d) x2 + y2 = 16
Answer:
(b) (x – 3)2 + (y + 4)2 = 16
Hint:
Centre (3, -4).
It touches the x-axis.
The absolute value of y-coordinate is the radius, i.e., radius = 4.
Equation is (x – 3)2 + (y + 4)2 = 16

Samacheer Kalvi 11th Business Maths Guide Chapter 3 Analytical Geometry Ex 3.7

Question 21.
If the circle touches the x-axis, y-axis, and the line x = 6 then the length of the diameter of the circle is:
(a) 6
(b) 3
(c) 12
(d) 4
Answer:
(a) 6
Hint:
Samacheer Kalvi 11th Business Maths Guide Chapter 3 Analytical Geometry Ex 3.7 Q21

Question 22.
The eccentricity of the parabola is:
(a) 3
(b) 2
(c) 0
(d) 1
Answer:
(d) 1

Samacheer Kalvi 11th Business Maths Guide Chapter 3 Analytical Geometry Ex 3.7

Question 23.
The double ordinate passing through the focus is:
(a) focal chord
(b) latus rectum
(c) directrix
(d) axis
Answer:
(b) latus rectum
Hint:
Samacheer Kalvi 11th Business Maths Guide Chapter 3 Analytical Geometry Ex 3.7 Q23

Question 24.
The distance between directrix and focus of a parabola y2 = 4ax is:
(a) a
(b) 2a
(c) 4a
(d) 3a
Answer:
(b) 2a

Samacheer Kalvi 11th Business Maths Guide Chapter 3 Analytical Geometry Ex 3.7

Question 25.
The equation of directrix of the parabola y2 = -x is:
(a) 4x + 1 = 0
(b) 4x – 1 = 0
(c) x – 1 = 0
(d) x + 4 = 0
Answer:
(b) 4x – 1 = 0
Hint:
y2 = -x.
It is a parabola open leftwards.
Here 4a = 1 ⇒ a = \(\frac{1}{4}\)
Equation of directrix is x = a.
i.e., x = \(\frac{1}{4}\) (or) 4x – 1 = 0

Samacheer Kalvi 11th Business Maths Guide Chapter 3 Analytical Geometry Ex 3.6

Students can download 11th Business Maths Chapter 3 Analytical Geometry Ex 3.6 Questions and Answers, Notes, Samcheer Kalvi 11th Business Maths Guide Pdf helps you to revise the complete Tamilnadu State Board New Syllabus, helps students complete homework assignments and to score high marks in board exams.

Tamilnadu Samacheer Kalvi 11th Business Maths Solutions Chapter 3 Analytical Geometry Ex 3.6

Samacheer Kalvi 11th Business Maths Analytical Geometry Ex 3.6 Text Book Back Questions and Answers

Question 1.
Find the equation of the parabola whose focus is the point F(-1, -2) and the directrix is the line 4x – 3y + 2 = 0.
Solution:
F(-1, -2)
l : 4x – 3y + 2 = 0
Let P(x, y) be any point on the parabola.
FP = PM
⇒ FP2 = PM2
⇒ (x + 1)2 + (y + 2)2 = \(\left[\frac{4 x-3 y+2}{\sqrt{4^{2}+(-3)^{2}}}\right]^{2}\)
⇒ x2 + 2x + 1 + y2 + 4y + 4 = \(\frac{16 x^{2}+9 y^{2}+4-24 x y+16 x-12 y}{(16+9)}\)
⇒ 25(x2 + y2 + 2x + 4y + 5) = 16x2 + 9y2 – 24xy + 16x – 12y + 4
⇒ (25 – 16)x2 + (25 – 9)y2 + 24xy + (50 – 16)x + (100 + 12)y + 125 – 4 = 0
⇒ 9x2 + 16y2 + 24xy + 34x + 112y + 121 = 0

Samacheer Kalvi 11th Business Maths Guide Chapter 3 Analytical Geometry Ex 3.6

Question 2.
The parabola y2 = kx passes through the point (4, -2). Find its latus rectum and focus.
Solution:
y2 = kx passes through (4, -2)
(-2)2 = k(4)
⇒ 4 = 4k
⇒ k = 1
y2 = x = 4(\(\frac{1}{4}\))x
a = \(\frac{1}{4}\)
Equation of LR is x = a or x – a = 0
i.e., x = \(\frac{1}{4}\)
⇒ 4x = 1
⇒ 4x – 1 = 0
Focus (a, 0) = (\(\frac{1}{4}\), 0)

Question 3.
Find the vertex, focus, axis, directrix, and the length of the latus rectum of the parabola y2 – 8y – 8x + 24 = 0.
Solution:
y2 – 8y – 8x + 24 = 0
⇒ y2 – 8y – 42 = 8x – 24 + 42
⇒ (y – 4)2 = 8x – 8
⇒ (y – 4)2 = 8(x – 1)
⇒ (y – 4)2 = 4(2) (x – 1)
∴ a = 2
Y2 = 4(2)X where X = x – 1 and Y = y – 4
Samacheer Kalvi 11th Business Maths Guide Chapter 3 Analytical Geometry Ex 3.6 Q3

Samacheer Kalvi 11th Business Maths Guide Chapter 3 Analytical Geometry Ex 3.6

Question 4.
Find the co-ordinates of the focus, vertex, equation of the directrix, axis and the length of latus rectum of the parabola (a) y2 = 20x, (b) x2 = 8y, (c) x2 = -16y
Solution:
(a) y2 = 20x
y2 = 4(5)x
∴ a = 5
Samacheer Kalvi 11th Business Maths Guide Chapter 3 Analytical Geometry Ex 3.6 Q4

(b) x2 = 8y = 4(2)y
∴ a = 2
Samacheer Kalvi 11th Business Maths Guide Chapter 3 Analytical Geometry Ex 3.6 Q4.1

(c) x2 = -16y = -4(4)y
∴ a = 4
Samacheer Kalvi 11th Business Maths Guide Chapter 3 Analytical Geometry Ex 3.6 Q4.2

Question 5.
The average variable cost of the monthly output of x tonnes of a firm producing a valuable metal is ₹ \(\frac{1}{5}\) x2 – 6x + 100. Show that the average variable cost curve is a parabola. Also, find the output and the average cost at the vertex of the parabola.
Solution:
Let output be x and average variable cost = y
y = \(\frac{1}{5}\) x2 – 6x + 100
⇒ 5y = x2 – 30x + 500
⇒ x2 – 30x + 225 = 5y – 500 + 225
⇒ (x – 15)2 = 5y – 275
⇒ (x – 15)2 = 5(y – 55) which is of the form X2 = 4(\(\frac{5}{4}\))Y
∴ Y average variable cost curve is a parabola
Vertex (0, 0)
x – 15 = 0; y – 55 = 0
x = 15; y = 55
At the vertex, output is 15 tonnes and average cost is ₹ 55.

Samacheer Kalvi 11th Business Maths Guide Chapter 3 Analytical Geometry Ex 3.6

Question 6.
The profit ₹ y accumulated in thousand in x months is given by y = -x2 + 10x – 15. Find the best time to end the project.
Solution:
y = -x2 + 10x – 15
⇒ y = -[x2 – 10x + 52 – 52 + 15]
⇒ y = -[(x – 5)2 – 10]
⇒ y = 10 – (x – 5)2
⇒ (x – 5)2 = -(y – 10)
This is a parabola which is open downwards.
Vertex is the maximum point.
∴ Profit is maximum when x – 5 = 0 (or) x = 5 months.
After that profit gradually reduces.
∴ The best time to end the project is after 5 months.

Samacheer Kalvi 11th Business Maths Guide Chapter 3 Analytical Geometry Ex 3.5

Students can download 11th Business Maths Chapter 3 Analytical Geometry Ex 3.5 Questions and Answers, Notes, Samcheer Kalvi 11th Business Maths Guide Pdf helps you to revise the complete Tamilnadu State Board New Syllabus, helps students complete homework assignments and to score high marks in board exams.

Tamilnadu Samacheer Kalvi 11th Business Maths Solutions Chapter 3 Analytical Geometry Ex 3.5

Samacheer Kalvi 11th Business Maths Analytical Geometry Ex 3.5 Text Book Back Questions and Answers

Question 1.
Find the equation of the tangent to the circle x2 + y2 – 4x + 4y – 8 = 0 at (-2, -2).
Solution:
The equation of the tangent to the circle x2 + y2 – 4x + 4y – 8 = 0 at (x1, y1) is
xx1 + yy1 – 4\(\frac{\left(x+x_{1}\right)}{2}\) + 4\(\frac{\left(y+y_{1}\right)}{2}\) – 8 = 0
Here (x1, y1) = (-2, -2)
⇒ x(-2) + y(-2) – 2(x – 2) + 2(y – 2) – 8 = 0
⇒ -2x – 2y – 2x + 4 + 2y – 4 – 8 = 0
⇒ -4x – 8 = 0
⇒ x + 2 = 0

Samacheer Kalvi 11th Business Maths Guide Chapter 3 Analytical Geometry Ex 3.5

Question 2.
Determine whether the points P(1, 0), Q(2, 1) and R(2, 3) lie outside the circle, on the circle or inside the circle x2 + y2 – 4x – 6y + 9 = 0.
Solution:
The equation of the circle is x2 + y2 – 4x – 6y + 9 = 0
PT2 = \(x_{1}^{2}+y_{1}^{2}\) – 4x1 – 6y1 + 9
At P(1, 0), PT2 = 1 + 0 – 4 – 0 + 9 = 6 > 0
At Q(2, 1), PT2 = 4 + 1 – 8 – 6 + 9 = 0
At R(2, 3), PT2 = 4 + 9 – 8 – 18 + 9 = -4 < 0
The point P lies outside the circle.
The point Q lies on the circle.
The point R lies inside the circle.

Question 3.
Find the length of the tangent from (1, 2) to the circle x2 + y2 – 2x + 4y + 9 = 0.
Solution:
The length of the tangent from (x1, y1) to the circle x2 + y2 – 2x + 4y + 9 = 0 is \(\sqrt{x_{1}^{2}+y_{1}^{2}-2 x_{1}+4 y_{1}+9}\)
Length of the tangent from (1, 2) = \(\sqrt{1^{2}+2^{2}-2(1)+4(2)+9}\)
= \(\sqrt{1+4-2+8+9}\)
= \(\sqrt{20}\)
= \(\sqrt{4 \times 5}\)
= 2√5 units

Samacheer Kalvi 11th Business Maths Guide Chapter 3 Analytical Geometry Ex 3.5

Question 4.
Find the value of P if the line 3x + 4y – P = 0 is a tangent to the circle x2 + y2 = 16.
Solution:
The condition for a line y = mx + c to be a tangent to the circle x2 + y2 = a2 is c2 = a2 (1 + m2)
Equation of the line is 3x + 4y – P = 0
Equation of the circle is x2 + y2 = 16
4y = -3x + P
y = \(\frac{-3}{4} x+\frac{P}{4}\)
∴ m = \(\frac{-3}{4}\), c = \(\frac{P}{4}\)
Equation of the circle is x2 + y2 = 16
∴ a2 = 16
Condition for tangency we have c2 = a2(1 + m2)
⇒ \(\left(\frac{P}{4}\right)^{2}=16\left(1+\frac{9}{16}\right)\)
⇒ \(\frac{P^{2}}{16}=16\left(\frac{25}{16}\right)\)
⇒ P2 = 16 × 25
⇒ P = ±√16√25
⇒ P = ±4 × 5
⇒ P = ±20

Samacheer Kalvi 11th Business Maths Guide Chapter 3 Analytical Geometry Ex 3.4

Students can download 11th Business Maths Chapter 3 Analytical Geometry Ex 3.4 Questions and Answers, Notes, Samcheer Kalvi 11th Business Maths Guide Pdf helps you to revise the complete Tamilnadu State Board New Syllabus, helps students complete homework assignments and to score high marks in board exams.

Tamilnadu Samacheer Kalvi 11th Business Maths Solutions Chapter 3 Analytical Geometry Ex 3.4

Samacheer Kalvi 11th Business Maths Analytical Geometry Ex 3.4 Text Book Back Questions and Answers

Question 1.
Find the equation of the following circles having
(i) the centre (3, 5) and radius 5 units.
(ii) the centre (0, 0) and radius 2 units.
Solution:
(i) Equation of the circle is (x – h)2 + (y – k)2 = r2
Centre (h, k) = (3, 5) and radius r = 5
∴ Equation of the circle is (x – 3)2 + (y – 5)2 = 52
⇒ x2 – 6x + 9 + y2 – 10y + 25 = 25
⇒ x2 + y2 – 6x – 10y + 9 = 0

(ii) Equation of the circle when centre origin (0, 0) and radius r is x2 + y2 = r2
⇒ x2 + y2 = 22
⇒ x2 + y2 = 4
⇒ x2 + y2 – 4 = 0

Question 2.
Find the centre and radius of the circle
(i) x2 + y2 = 16
(ii) x2 + y2 – 22x – 4y + 25 = 0
(iii) 5x2 + 5y2+ 4x – 8y – 16 = 0
(iv) (x + 2) (x – 5) + (y – 2) (y – 1) = 0
Solution:
(i) x2 + y2 = 16
⇒ x2 + y2 = 42
This is a circle whose centre is origin (0, 0), radius 4.

(ii) Comparing x2 + y2 – 22x – 4y + 25 = 0 with general equation of circle x2 + y2 + 2gx + 2fy + c = 0
We get 2g = -22, 2f = -4, c = 25
g = -11, f = -2, c = 25
Centre = (-g, -f) = (11, 2)
Samacheer Kalvi 11th Business Maths Guide Chapter 3 Analytical Geometry Ex 3.4 Q2

(iii) 5x2 + 5y2 + 4x – 8y – 16 = 0
To make coefficient of x2 unity, divide the equation by 5 we get,
\(x^{2}+y^{2}+\frac{4}{5} x-\frac{8}{5} y-\frac{16}{5}=0\)
Comparing the above equation with x2 + y2 + 2gx + 2fy + c = 0 we get,
Samacheer Kalvi 11th Business Maths Guide Chapter 3 Analytical Geometry Ex 3.4 Q2.1
Samacheer Kalvi 11th Business Maths Guide Chapter 3 Analytical Geometry Ex 3.4 Q2.2

(iv) Equation of the circle is (x + 2) (x – 5) + (y – 2) (y – 1) = 0
x2 – 3x – 10 + y2 – 3y + 2 = 0
x2 + y2 – 3x – 3y – 8 = 0
Comparing this with x2 + y2 + 2gx + 2fy + c = 0
We get 2g = -3, 2f = -3, c = -8
g = \(\frac{-3}{2}\), f = \(\frac{-3}{2}\), c = -8
Centre (-g, -f) = \(\left(\frac{3}{2}, \frac{3}{2}\right)\)
Samacheer Kalvi 11th Business Maths Guide Chapter 3 Analytical Geometry Ex 3.4 Q2.3

Samacheer Kalvi 11th Business Maths Guide Chapter 3 Analytical Geometry Ex 3.4

Question 3.
Find the equation of the circle whose centre is (-3, -2) and having circumference 16π.
Solution:
Circumference, 2πr = 16π
⇒ 2r = 16
⇒ r = 8
Equation of the circle when centre and radius are known is (x – h)2 + (y – k)2 = r2
⇒ (x + 3)2 + (y + 2)2 = 82
⇒ x2 + 6x + 9 + y2 + 4y + 4 = 64
⇒ x2 + y2 + 6x + 4y + 13 = 64
⇒ x2 + y2 + 6x + 4y – 51 = 0

Question 4.
Find the equation of the circle whose centre is (2, 3) and which passes through (1, 4).
Solution:
Samacheer Kalvi 11th Business Maths Guide Chapter 3 Analytical Geometry Ex 3.4 Q4
Centre (h, k) = (2, 3)
Samacheer Kalvi 11th Business Maths Guide Chapter 3 Analytical Geometry Ex 3.4 Q4.1
Equation of the circle with centre (h, k) and radius r is (x – h)2 + (y – k)2 = r2
⇒ (x – 2)2 + (y – 3)2 = (√2)2
⇒ x2 – 4x + 4 + y2 – 6y + 9 = 2
⇒ x2 + y2 – 4x – 6y + 11 = 0

Samacheer Kalvi 11th Business Maths Guide Chapter 3 Analytical Geometry Ex 3.4

Question 5.
Find the equation of the circle passing through the points (0, 1), (4, 3) and (1, -1).
Solution:
Let the required of the circle be x2 + y2 + 2gx + 2fy + c = 0 ……… (1)
It passes through (0, 1)
0 + 1 + 2g(0) + 2f(1) + c = 0
1 + 2f + c = 0
2f + c = -1 …….. (2)
Again the circle (1) passes through (4, 3)
42 + 32 + 2g(4) + 2f(3) + c = 0
16 + 9 + 8g + 6f + c = 0
8g + 6f + c = -25 …….. (3)
Again the circle (1) passes through (1, -1)
12 + (-1)2 + 2g(1) + 2f(-1) + c = 0
1 + 1 + 2g – 2f + c = 0
2g – 2f + c = -2 ……… (4)
8g + 6f + c = -25
(4) × 4 subtracting we get, 8g – 8f + 4c = -8
14f – 3c = -17 ………. (5)
14f – 3c = -17
(2) × 3 ⇒ 6f + 3c = -3
Adding we get 20f = -20
f = -1
Using f = -1 in (2) we get, 2(-1) + c = -1
c = -1 + 2
c = 1
Using f = -1, c = 1 in (3) we get
8g + 6(-1)+1 = -25
8g – 6 + 1 = -25
8g – 5 = -25
8g = -20
g = \(\frac{-20}{8}=\frac{-5}{2}\)
using g = \(\frac{-5}{2}\), f = -1, c = 1 in (1) we get the equation of the circle.
x2 + y2 + 2(\(\frac{-5}{2}\))x + 2(-1)y + 1 = 0
x2 + y2 – 5x – 2y + 1 = 0

Question 6.
Find the equation of the circle on the line joining the points (1, 0), (0, 1), and having its centre on the line x + y = 1.
Solution:
Samacheer Kalvi 11th Business Maths Guide Chapter 3 Analytical Geometry Ex 3.4 Q6
Let the equation of the circle be
x2 + y2 + 2gx + 2fy + c = 0 ……… (1)
The circle passes through (1, 0)
12 + 02 + 2g(1) + 2f(0) + c = 0
1 + 2g + c = 0
2g + c = 1 …….. (2)
Again the circle (1) passes through (0, 1)
02 + 12 + 2g(0) + 2f(1) + c = 0
1 + 2f + c = 0
2f + c = -1 ……. (3)
(2) – (3) gives 2g – 2f = 0 (or) g – f = 0 ………. (4)
Given that the centre of the circle (-g, -f) lies on the line x + y = 1
-g – f = 1 …….. (5)
(4) + (5) gives -2f = 1 ⇒ f = \(-\frac{1}{2}\)
Using f = \(-\frac{1}{2}\) in (5) we get
-g – (\(-\frac{1}{2}\)) = 1
-g = 1 – \(-\frac{1}{2}\) = \(\frac{1}{2}\)
g = \(-\frac{1}{2}\)
Using g = \(-\frac{1}{2}\) in (2) we get
2(\(-\frac{1}{2}\)) + c = -1
-1 + c = -1
c = 0
using g = \(-\frac{1}{2}\), f = \(-\frac{1}{2}\), c = 0 in (1) we get the equation of the circle,
x2 + y2 + 2(\(-\frac{1}{2}\))x + 2(\(-\frac{1}{2}\))y + 0 = 0
x2 + y2 – x – y = 0

Samacheer Kalvi 11th Business Maths Guide Chapter 3 Analytical Geometry Ex 3.4

Question 7.
If the lines x + y = 6 and x + 2y = 4 are diameters of the circle, and the circle passes through the point (2, 6) then find its equation.
Solution:
To get coordinates of centre we should solve the equations of the diameters x + y = 6, x + 2y = 4.
x + y = 6 ……. (1)
x + 2y = 4 ………. (2)
(1) – (2) ⇒ -y = 2
y = -2
Using y = -2 in (1) we get x – 2 = 6
x = 8
Centre is (8, -2) the circle passes through the point (2, 6).
Samacheer Kalvi 11th Business Maths Guide Chapter 3 Analytical Geometry Ex 3.4 Q7
Equation of the circle with centre (h, k) and radius r is (x – h)2 + (y – k)2 = r2
⇒ (x – 8)2 + (y + 2)2 = 102
⇒ x2 + y2 – 16x + 4y + 64 + 4 = 100
⇒ x2 + y2 – 16x + 4y – 32 = 0

Question 8.
Find the equation of the circle having (4, 7) and (-2, 5) as the extremities of a diameter.
Solution:
The equation of the circle when entremities (x1, y1) and (x2, y2) are given is (x – x1) (x – x2) + (y – y1) (y – y2) = 0
⇒ (x – 4) (x + 2) + (y – 7) (y – 5) = 0
⇒ x2 – 2x – 8 + y2 – 12y + 35 = 0
⇒ x2 + y2 – 2x – 12y + 27 = 0

Samacheer Kalvi 11th Business Maths Guide Chapter 3 Analytical Geometry Ex 3.4

Question 9.
Find the Cartesian equation of the circle whose parametric equations are x = 3 cos θ, y = 3 sin θ, 0 ≤ θ ≤ 2π.
Solution:
Given x = 3 cos θ, y = 3 sin θ
Now x2 + y2 = 9 cos2θ + 9 sin2θ
x2 + y2 = 9 (cos2θ + sin2θ)
x2 + y2 = 9 which is the Cartesian equation of the required circle.

Samacheer Kalvi 11th Business Maths Guide Chapter 3 Analytical Geometry Ex 3.3

Students can download 11th Business Maths Chapter 3 Analytical Geometry Ex 3.3 Questions and Answers, Notes, Samcheer Kalvi 11th Business Maths Guide Pdf helps you to revise the complete Tamilnadu State Board New Syllabus, helps students complete homework assignments and to score high marks in board exams.

Tamilnadu Samacheer Kalvi 11th Business Maths Solutions Chapter 3 Analytical Geometry Ex 3.3

Samacheer Kalvi 11th Business Maths Analytical Geometry Ex 3.3 Text Book Back Questions and Answers

Question 1.
If the equation ax2 + 5xy – 6y2 + 12x + 5y + c = 0 represents a pair of perpendicular straight lines, find a and c.
Solution:
Comparing ax2 + 5xy – 6y2 + 12x + 5y + c = 0 with ax2 + 2hxy + by2 + 2gx + 2fy + c = 0
We get a = a, 2h = 5, (or) h = \(\frac{5}{2}\), b = -6, 2g = 12 (or) g = 6, 2f = 5 (or) f = \(\frac{5}{2}\), c = c
Condition for pair of straight lines to be perpendicular is a + b = 0
a + (-6) = 0
a = 6
Next to find c. Condition for the given equation to represent a pair of straight lines is
Samacheer Kalvi 11th Business Maths Guide Chapter 3 Analytical Geometry Ex 3.3 Q1
R1 → R1 – R3
Expanding along first row we get 0 – 0 + (6 – c) [\(\frac{25}{4}\) + 36] = 0
(6-c) [\(\frac{25}{4}\) + 36] = 0
6 – c = 0
6 = c (or) c = 6

Samacheer Kalvi 11th Business Maths Guide Chapter 3 Analytical Geometry Ex 3.3

Question 2.
Show that the equation 12x2 – 10xy + 2y2 + 14x – 5y + 2 = 0 represents a pair of straight lines and also find the separate equations of the straight lines.
Solution:
Comparing 12x2 – 10xy + 2y2 + 14x – 5y + 2 = 0 with ax2 + 2hxy + by2 + 2gh + 2fy + c = 0
We get a = 12, 2h = -10, (or) h = -5, b = 2, 2g = 14 (or) g = 7, 2f = -5 (or) f = \(-\frac{5}{2}\), c = 2
Condition for the given equation to represent a pair of straight lines is \(\left|\begin{array}{lll}
a & h & g \\
h & b & f \\
g & f & c
\end{array}\right|=0\)
\(\left|\begin{array}{lll}
a & h & g \\
h & b & f \\
g & f & c
\end{array}\right|=\left|\begin{array}{rrr}
12 & -5 & 7 \\
-5 & 2 & \frac{-5}{2} \\
7 & \frac{-5}{2} & 2
\end{array}\right|\)
Samacheer Kalvi 11th Business Maths Guide Chapter 3 Analytical Geometry Ex 3.3 Q2
= \(\frac{1}{4}\) [12(16 – 25) + 5(-40 + 70) + 7(50 – 56)]
= \(\frac{1}{4}\) [12(-9) + 5(30) + 7(-6)]
= \(\frac{1}{4}\) [-108 + 150 – 42]
= \(\frac{1}{4}\) [0]
= 0
∴ The given equation represents a pair of straight lines.
Consider 12x2 – 10xy + 2y2 = 2[6x2 – 5xy + y2] = 2[(3x – y)(2x – y)] = (6x – 2y)(2x – y)
Let the separate equations be 6x – 2y + l = 0, 2x – y + m = 0
To find l, m
Let 12x2 – 10xy + 2y2 + 14x – 5y + 2 = (6x – 2y + l) (2x – y + m) ……. (1)
Equating coefficient of y on both sides of (1) we get
2l + 6m = 14 (or) l + 3m = 7 ………… (2)
Equating coefficient of x on both sides of (1) we get
-l – 2m = -5 ……… (3)
(2) + (3) ⇒ m = 2
Using m = 2 in (2) we get
l + 3(2) = 7
l = 7 – 6
l = 1
∴ The separate equations are 6x – 2y + 1 = 0, 2x – y + 2 = 0.

Samacheer Kalvi 11th Business Maths Guide Chapter 3 Analytical Geometry Ex 3.3

Question 3.
Show that the pair of straight lines 4x2 + 12xy + 9y2 – 6x – 9y + 2 = 0 represents two parallel straight lines and also find the separate equations of the straight lines.
Solution:
The given equation is 4x2 + 12xy + 9y2 – 6x – 9y + 2 = 0
Here a = 4, 2h = 12, (or) h = 6 and b = 9
h2 – ab = 62 – 4 × 9 = 36 – 36 = 0
∴ The given equation represents a pair of parallel straight lines
Consider 4x2 + 12xy + 9y2 = (2x)2 + 12xy + (3y)2
= (2x)2 + 2(2x)(3y) + (3y)2
= (2x + 3y)2
Here we have repeated factors.
Now consider, 4x2 + 12xy + 9y2 – 6x – 9y + 2 = 0
(2x + 3y)2 – 3(2x + 3y) + 2 = 0
t2 – 3t + 2 = 0 where t = 2x + 3y
(t – 1)(t – 2) = 0
(2x + 3y – 1) (2x + 3y – 2) = 0
∴ Separate equations are 2x + 3y – 1 = 0, 2x + 3y – 2 = 0

Samacheer Kalvi 11th Business Maths Guide Chapter 3 Analytical Geometry Ex 3.3

Question 4.
Find the angle between the pair of straight lines 3x2 – 5xy – 2y2 + 17x + y + 10 = 0.
Solution:
The given equation is 3x2 – 5xy – 2y2 + 17x + y + 10 = 0
Here a = 3, 2h = -5, b = -2
If θ is the angle between the given straight lines then
Samacheer Kalvi 11th Business Maths Guide Chapter 3 Analytical Geometry Ex 3.3 Q4

Tamil Nadu 11th Maths Model Question Papers 2020-2021 English Tamil Medium

Subject Matter Experts at SamacheerKalvi.Guide have created Samacheer Kalvi Tamil Nadu State Board Syllabus New Paper Pattern 11th Maths Model Question Papers 2020-2021 with Answers Pdf Free Download in English Medium and Tamil Medium of TN 11th Standard Maths Public Exam Question Papers Answer Key, New Paper Pattern of HSC 11th Class Maths Previous Year Question Papers, Plus One +1 Maths Model Sample Papers are part of Tamil Nadu 11th Model Question Papers.

Let us look at these Government of Tamil Nadu State Board 11th Maths Model Question Papers Tamil Medium with Answers 2020-21 Pdf. Students can view or download the Class 11th Maths New Model Question Papers 2021 Tamil Nadu English Medium Pdf for their upcoming Tamil Nadu HSC Board Exams. Students can also read Tamilnadu Samcheer Kalvi 11th Maths Guide.

TN State Board 11th Maths Model Question Papers 2020 2021 English Tamil Medium

Tamil Nadu 11th Maths Model Question Papers English Medium 2020-2021

Tamil Nadu 11th Maths Model Question Papers Tamil Medium 2019-2020

  • Tamil Nadu 11th Maths Model Question Paper 1 Tamil Medium
  • Tamil Nadu 11th Maths Model Question Paper 2 Tamil Medium
  • Tamil Nadu 11th Maths Model Question Paper 3 Tamil Medium
  • Tamil Nadu 11th Maths Model Question Paper 4 Tamil Medium
  • Tamil Nadu 11th Maths Model Question Paper 5 Tamil Medium

11th Maths Model Question Paper Design 2020-2021 Tamil Nadu

Types of QuestionsMarksNo. of Questions to be AnsweredTotal Marks
Part-I Objective Type12020
Part-II Very Short Answers
(Totally 10 questions will be given. Answer any Seven. Any one question should be answered compulsorily)
2714
Part-Ill Short Answers
(Totally 10 questions will be given. Answer any Seven. Any one question should be answered compulsorily)
3727
Part-IV Essay Type5735
Total90
Internal Assesment10
Total Marks100

Tamil Nadu 11th Maths Model Question Paper Weightage of Marks

PurposeWeightage
1. Knowledge30%
2. Understanding40%
3. Application20%
4. Skill/Creativity10%

It is necessary that students will understand the new pattern and style of Model Question Papers of 11th Standard Maths Tamilnadu State Board Syllabus according to the latest exam pattern. These Tamil Nadu Plus One 11th Maths Model Question Papers State Board Tamil Medium and English Medium are useful to understand the pattern of questions asked in the board exam. Know about the important concepts to be prepared for TN HSLC Board Exams and Score More marks.

We hope the given Samacheer Kalvi Tamil Nadu State Board Syllabus New Paper Pattern Class 11th Maths Model Question Papers 2020 2021 with Answers Pdf Free Download in English Medium and Tamil Medium will help you get through your subjective questions in the exam.

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