Number of solutions of the equation $\tan ^2 x+3 \cot ^2 x=2 \sec ^2 x$ lying in the interval $[0,2 \pi]$ is

If $2 \sin \theta+3 \cos \theta=2$ and $\theta \neq(2 n+1) \frac{\pi}{2}$, then $\sin \theta+\cos \theta=$

If $x \in(-\pi, \pi)$, then the number of solutions of the equation $2 \sin x \sin 3 x \sin 5 x+\sin 5 x \cos 4 x=0$ is

If $\cos \alpha+\cos \beta+\cos \gamma=0=\sin \alpha+\sin \beta+\sin \gamma$, then $\sin 2 \alpha+\sin 2 \beta+\sin 2 \gamma=$