Trigonometric Equations Question 93
Question: If cot $ (\alpha +\beta )=0, $ then $ \sin (\alpha +2\beta )= $
[Kerala (Engg.) 2001]
Options:
A) $ \sin \alpha $
B) $ \cos \alpha $
C) $ \sin \beta $
D) $ \cos 2\beta $
Show Answer
Answer:
Correct Answer: A
Solution:
- Given, cot $ (\alpha +\beta )=0\Rightarrow \cos (\alpha +\beta )=0 $
Þ $ \alpha +\beta =(2n+1)\frac{\pi }{2},n\in I $ \ $ \sin (\alpha +2\beta )=\sin (2\alpha +2\beta -\alpha ) $ = $ \sin [(2n+1)\pi -\alpha ] $ $ =\sin (,2n\pi +\pi -\alpha ,) $ = $ \sin (,\pi -\alpha ,),=\sin \alpha $ .
BETA
