Question
यदि $\sin 3\alpha  = 4\sin \alpha \sin (x + \alpha )\sin (x - \alpha ),$ तब $x = $

Answer

b
(b) $3\sin \alpha - 4{\sin ^3}\alpha = 4\sin \alpha ({\sin ^2}x - {\sin ^2}\alpha )$

$\therefore $ ${\sin ^2}x = {\left( {\frac{{\sqrt 3 }}{2}} \right)^2}$ 

==> ${\sin ^2}x = {\sin ^2}\pi /3$

==> $x = n\pi \pm \pi /3$.

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