If $\cot (\alpha + \beta ) = 0,$ then $\sin (\alpha + 2\beta ) = $
$\sin \alpha $
$\cos \alpha $
$\sin \beta $
$\cos 2\beta $
The equation $3\cos x + 4\sin x = 6$ has
If $\operatorname{cosec}^2(\alpha+\beta)-\sin ^2(\beta-\alpha)+\sin ^2(2 \alpha-\beta)=\cos ^2(\alpha-\beta)$ where $\alpha, \beta \in\left(0, \frac{\pi}{2}\right)$, then $\sin (\alpha-\beta)$ is equal to
The number of solution of the equation,$\sum\limits_{r = 1}^5 {\cos (r\,x)} $ $= 0$ lying in $(0, \pi)$ is :
If $1 + \sin x + {\sin ^2}x + .....$ to $\infty = 4 + 2\sqrt 3 ,\,0 < x < \pi ,$ then
Find the general solution of the equation $\cos 3 x+\cos x-\cos 2 x=0$