Trigonometric Equations Question 246
Question: If $ \sin 2x+\sin 4x=2\sin 3x, $ then $ x $ =
[EAMCET 1989]
Options:
A) $ \frac{n\pi }{3} $
B) $ n\pi +\frac{\pi }{3} $
C) $ 2n\pi \pm \frac{\pi }{3} $
D) None of these
Show Answer
Answer:
Correct Answer: A
Solution:
- $ 2\sin 3x\cos x-2\sin 3x=0 $ ,
$ \therefore $ $ \sin 3x=0 $ , $ \cos x=1 $ $ \frac{1}{2}=\frac{\frac{3h}{120}-\frac{h}{120}}{1+\frac{3h^{2}}{14400}}\Rightarrow h=120,,40 $ $ 3x=n\pi $ or $ x=\frac{n\pi }{3} $ and $ x=2n\pi $ The second value $ x=2n\pi $ is included in the value given by $ x=\frac{n\pi }{3} $ .
BETA
