$\frac{{\sin 3\theta + \sin 5\theta + \sin 7\theta + \sin 9\theta }}{{\cos 3\theta + \cos 5\theta + \cos 7\theta + \cos 9\theta }} = $
$\tan 3\theta $
$\cot 3\theta $
$\tan 6\theta $
$\cot 6\theta $
यदि $\cos \,(\theta - \alpha ) = a,\,\,\sin \,(\theta - \beta ) = b,\,\,$ हो, तब ${\cos ^2}(\alpha - \beta ) + 2ab\,\sin \,(\alpha - \beta )$ बराबर है
$\tan \alpha + 2\tan 2\alpha + 4\tan 4\alpha + 8\cot \,8\alpha = $
यदि $x + y + z = {180^o},$ तो $\cos 2x + \cos 2y - \cos 2z$ बराबर है
$1 + \cos 2x + \cos 4x + \cos 6x = $
यदि $\sin \alpha = \frac{{ - 3}}{5},$ जहाँ $\pi < \alpha < \frac{{3\pi }}{2},$ तो $\cos \frac{1}{2}\alpha = $