Let $f(x) = \cos \sqrt {x,} $ then which of the following is true
$f(x)$ is periodic with period $\sqrt 2 \pi $
$f(x)$ is periodic with period $\sqrt \pi $
$f(x)$ is periodic with period $4{\pi ^2}$
$f(x)$ is not a periodic function
Let $S\, = \,\left\{ {\theta \, \in \,[ - \,2\,\pi ,\,\,2\,\pi ]\, :\,2\,{{\cos }^2}\,\theta \, + \,3\,\sin \,\theta \, = \,0} \right\}$. Then the sum of the elements of $S$ is
$2{\sin ^2}x + {\sin ^2}2x = 2,\, - \pi < x < \pi ,$ then $x = $
If $n$ is any integer, then the general solution of the equation $\cos x - \sin x = \frac{1}{{\sqrt 2 }}$ is
If $1 + \cot \theta = {\rm{cosec}}\theta $, then the general value of $\theta $ is
If $\frac{{1 - \cos 2\theta }}{{1 + \cos 2\theta }} = 3$, then the general value of $\theta $ is