The roots of the equation $1 - \cos \theta = \sin \theta .\sin \frac{\theta }{2}$ is
$k\pi ,k \in I$
$2k\pi ,k \in I$
$k\frac{\pi }{2},k \in I$
None of these
The positive integer value of $n>3$ satisfying the equation $\frac{1}{\sin \left(\frac{\pi}{n}\right)}=\frac{1}{\sin \left(\frac{2 \pi}{n}\right)}+\frac{1}{\sin \left(\frac{3 \pi}{n}\right)}$ is
The general value of $\theta $ satisfying ${\sin ^2}\theta + \sin \theta = 2$ is
If $4{\sin ^4}x + {\cos ^4}x = 1,$ then $x =$
The solution of $3\tan (A - {15^o}) = \tan (A + {15^o})$ is
Solve $\tan 2 x=-\cot \left(x+\frac{\pi}{3}\right)$