G9.2 There are exactly $n$ values of $\theta$ satisfying the equation $\left(\sin ^{2} \theta-1\right)\left(2 \sin ^{2} \theta-1\right)=0$, where $0^{\circ} \leq \theta \leq 360^{\circ}$. Find $n$.
$\begin{array}{l}\sin \theta= \pm 1, \pm \frac{1}{\sqrt{2}} \\ \theta=90^{\circ}, 270^{\circ}, 45^{\circ}, 135^{\circ}, 225^{\circ}, 315^{\circ} \\ n=6\end{array}$