જો $A + B + C = \pi ,$ તો ${\tan ^2}\frac{A}{2} + {\tan ^2}\frac{B}{2} + $${\tan ^2}\frac{C}{2}$ એ . . ..

$\left( {1 + \cos \frac{\pi }{8}} \right)\,\left( {1 + \cos \frac{{3\pi }}{8}} \right)\,\left( {1 + \cos \frac{{5\pi }}{8}} \right)\,\left( {1 + \cos \frac{{7\pi }}{8}} \right) = $

$\sqrt {\frac{{1 - \sin A}}{{1 + \sin A}}} = $

જો $A + B + C = {270^o},$ તો $\cos \,2A + \cos 2B + \cos 2C + 4\sin A\,\sin B\,\sin C = $

જો $\alpha + \beta - \gamma = \pi ,$ તો ${\sin ^2}\alpha + {\sin ^2}\beta - {\sin ^2}\gamma = $

$\cos \frac{\pi }{7}\cos \frac{{2\pi }}{7}\cos \frac{{3\pi }}{7} =$