If $\cos 2\theta=0$, then ${\begin{vmatrix}0 & \cos\theta & \sin\theta\\\cos\theta & \sin\theta & 0\\\sin\theta & 0 & \cos\theta\end{vmatrix}}^2$ =

Question

$\begin{array}{1 1} \frac{1}{2} \\ \frac{-1}{2} \\ \pm\frac{1}{2} \\ 0\end{array}$