If $A + B + C = \pi \,(A,B,C > 0)$ and the angle $C$ is obtuse then
$\tan A\,\tan B > 1$
$\tan A\,\tan B < 1$
$\tan A\,\,\tan B = 1$
None of these
$\left( {\frac{{\sin 2A}}{{1 + \cos 2A}}} \right)\,\left( {\frac{{\cos A}}{{1 + \cos A}}} \right)= $
If $\tan \alpha = \frac{1}{7},\;\tan \beta = \frac{1}{3},$ then $\cos 2\alpha = $
$\tan 20^\circ \tan 40^\circ \tan 60^\circ \tan 80^\circ = $
If $\alpha$, $\beta$,$\gamma$ are positive number such that $\alpha + \beta = \pi$ and $\beta + \gamma = \alpha$, then $tan\ \alpha$ is equal to - (where $\gamma \ne n\pi ,n \in I$ )
Given that $\cos \left( {\frac{{\alpha - \beta }}{2}} \right) = 2\cos \left( {\frac{{\alpha + B}}{2}} \right)$, then $\tan \frac{\alpha }{2}\tan \frac{\beta }{2} $ is equal to