Q. Total number of solutions of equation $\sin x . \tan 4 x=\cos x$ belonging to $(-\pi, 2 \pi)$ are:
Trigonometric Functions
Solution:
$\sin x \cdot \tan 4 x=\cos x $
$\Rightarrow \sin x \sin 4 x=\cos x \cos 4 x$
$\Rightarrow \cos 5 x=0 $
$\Rightarrow$ five solutions.
