જો $\cos \,(\theta - \alpha ) = a,\,\,\sin \,(\theta - \beta ) = b,\,\,$ તો ${\cos ^2}(\alpha - \beta ) + 2ab\,\sin \,(\alpha - \beta ) = . . . .$
$4{a^2}{b^2}$
${a^2} - {b^2}$
${a^2} + {b^2}$
$ - {a^2}{b^2}$
જો $A + B + C = {180^o},$ તો $\frac{{\tan A + \tan B + \tan C}}{{\tan A\,.\,\tan B\,.\,\tan C}} = $
$\cot {70^o} + 4\cos {70^o} = . . .$
$\cos 2(\theta + \phi ) - 4\cos (\theta + \phi )\sin \theta \sin \phi + 2{\sin ^2}\phi = $
સાબિત કરો કે, $=\frac{\sin 5 x-2 \sin 3 x+\sin x}{\cos 5 x-\cos x}=\tan x$
જો $\cos 3\theta = \alpha \cos \theta + \beta {\cos ^3}\theta ,$ તો $(\alpha ,\beta ) = $