જો $\cos \left( {\frac{{\alpha - \beta }}{2}} \right) = 2\cos \left( {\frac{{\alpha + B}}{2}} \right)$, તો $\tan \frac{\alpha }{2}\tan \frac{\beta }{2} = . . .$
$\frac{1}{2}$
$1\over3$
$\frac{1}{4}$
$\frac{1}{8}$
$cos^273^o + cos^247^o + (cos73^o . cos47^o )$ =
$1 + \cos \,{56^o} + \cos \,{58^o} - \cos {66^o} = $
જો $\tan x = \frac{b}{a},$ તો $\sqrt {\frac{{a + b}}{{a - b}}} + \sqrt {\frac{{a - b}}{{a + b}}} = $
$\sin \frac{\pi }{{14}}\sin \frac{{3\pi }}{{14}}\sin \frac{{5\pi }}{{14}}\sin \frac{{7\pi }}{{14}}\sin \frac{{9\pi }}{{14}}\sin \frac{{11\pi }}{{14}}\sin \frac{{13\pi }}{{14}} = . . . .$
સાબિત કરો કે, $\tan 3 x \tan 2 x \tan x=\tan 3 x-\tan 2 x-\tan x$