The principal solutions of $\cot x=\sqrt{3}$ are

$$\tan A+2 \tan 2 A+4 \tan 4 A+8 \cot 8 A=$$

The values of $x$ in $\left(0, \frac{\pi}{2}\right)$ satisfying the equation $\sin x \cos x=\frac{1}{4}$ are ..........

The number of solutions of $\sin ^2 \theta=\frac{1}{2}$ in $[0, \pi]$ is ..........