જો $A + B + C = \pi ,$ તો ${\tan ^2}\frac{A}{2} + {\tan ^2}\frac{B}{2} + $${\tan ^2}\frac{C}{2}$ એ . . ..
$ \le 1$
$ \ge 1$
$0$
$1$
$\cos \frac{\pi }{5}\cos \frac{{2\pi }}{5}\cos \frac{{4\pi }}{5}\cos \frac{{8\pi }}{5} = $
$\sin {20^o}\,\sin {40^o}\,\sin {60^o}\,\sin {80^o} = $
$\frac{{\tan {{70}^o} - \tan {{20}^o}}}{{\tan {{50}^o}}} = $
જો $a\tan \theta = b$, તો $a\cos 2\theta + b\sin 2\theta = $
જો $\sin \theta + \cos \theta = x,$ તો ${\sin ^6}\theta + {\cos ^6}\theta = \frac{1}{4}[4 - 3{({x^2} - 1)^2}]$ એ . . .. માટે શક્ય બને.