$\sqrt 3 \,{\rm{cosec}}\,{20^o} - \sec \,{20^o} = $
$2$
$\frac{{2\,\sin {{20}^o}}}{{\sin {{40}^o}}}$
$4$
$\frac{{4\,\sin {{20}^o}}}{{\sin {{40}^o}}}$
If $\tan x = \frac{b}{a},$ then $\sqrt {\frac{{a + b}}{{a - b}}} + \sqrt {\frac{{a - b}}{{a + b}}} = $
If $A$ and $B$ are complimentary angles, then :
$\frac{{\sin \theta + \sin 2\theta }}{{1 + \cos \theta + \cos 2\theta }} = $
${\sin ^4}\frac{\pi }{8} + {\sin ^4}\frac{{3\pi }}{8} + {\sin ^4}\frac{{5\pi }}{8} + {\sin ^4}\frac{{7\pi }}{8} = $
The value of $x$ that satisfies the relation $x = 1 - x + x^2 - x^3 + x^4 - x^5 + ......... \infty$