Trigonometric Identities Question 182
Question: If $ \sin {\theta_1}+\sin {\theta_2}+\sin {\theta_3}=3, $ then $ \cos {\theta_1}+\cos {\theta_2}+\cos {\theta_3}= $
[EAMCET 1994]
Options:
A) 3
B) 2
C) 1
D) 0
Show Answer
Answer:
Correct Answer: D
Solution:
$ \sin {\theta_1}+\sin {\theta_2}+\sin {\theta_3}=3 $
$ \Rightarrow \sin {\theta_1}=\sin {\theta_2}=\sin {\theta_3}=1 $ , $ (\because -1\le \sin x\le 1) $
$ \Rightarrow {\theta_1}={\theta_2}={\theta_3}=\frac{\pi }{2}\Rightarrow \cos {\theta_1}+\cos {\theta_2}+\cos {\theta_3}=0 $ .
BETA
