Trigonometric Equations Question 82
Question: If $ \cos A\sin ( A-\frac{\pi }{6} ) $ is maximum, then the value of A is equal to
Options:
A) $ \frac{\pi }{3} $
B) $ \frac{\pi }{4} $
C) $ \frac{\pi }{2} $
D) None of these
Show Answer
Answer:
Correct Answer: A
Solution:
- $ \cos A\sin ( A-\frac{\pi }{6} )=\frac{1}{2},[ \sin ( 2A-\frac{\pi }{6} )-\sin \frac{\pi }{6} ] $ But $ \sin ( 2A-\frac{\pi }{6} )-\frac{1}{2} $ attain maximum value at $ 2A-\frac{\pi }{6}=\frac{\pi }{2}\Rightarrow A=\frac{\pi }{3} $ .
BETA
