The value of $\tan ( - 945^\circ )$ is
Convert $6$ radians into degree measure.
Prove that: $(\cos x+\cos y)^{2}+(\sin x-\sin y)^{2}=4 \cos ^{2} \frac{x+y}{2}$
Find the radian measures corresponding to the following degree measures:
$520^{\circ}$
If $\sin A,\cos A$ and $\tan A$ are in $G.P.$, then ${\cos ^3}A + {\cos ^2}A$ is equal to