If $2y\,\cos \theta = x\sin \,\theta {\rm{ and }}2x\sec \theta - y\,{\rm{cosec}}\,\theta = 3,$ then ${x^2} + 4{y^2} = $
$4$
$-4$
$± 4$
None of these
The value of $\sin 10^\circ + \sin 20^\circ + \sin 30^\circ + ... + $ $\sin 360^\circ $ is
Convert $6$ radians into degree measure.
$(m + 2)\sin \theta + (2m - 1)\cos \theta = 2m + 1,$ if
Find the value of $\sin \frac{31 \pi}{3}$.
If $\tan \theta = - \frac{1}{{\sqrt {10} }}$ and $\theta $ lies in the fourth quadrant, then $\cos \theta = $