Trigonometric Equations Question 262
Question: If in a triangle the angles are in A. P. and $ b:c=\sqrt{3}:\sqrt{2} $ , then $ \angle A $ is equal to
[IIT 1981; Kurukshetra CEE 1998; Pb. CET 1990]
Options:
A) $ 30^{o} $
B) $ 60^{o} $
C) $ 15^{o} $
D) $ 75^{o} $
Show Answer
Answer:
Correct Answer: D
Solution:
- Since the angles are in A.P., therefore $ B=60^{o} $ and $ \frac{b}{c}=\frac{\sin B}{\sin C}=\frac{\sqrt{3}}{\sqrt{2}}=\frac{\sqrt{3}}{2\sin C}=\frac{\sqrt{3}}{\sqrt{2}} $
Þ $ C=45^{o} $ so that $ A=180^{o}-60^{o}-45^{o}=75^{o} $ .
BETA
