If $\alpha$ and $\beta$ are the roots of the quadratic equation, $x^2+x \sin \theta-2 \sin \theta=0, \quad \theta \in\left(0, \frac{\pi}{2}\right)$, then $\frac{\alpha^{12}+\beta^{12}}{\left(a^{-12}+\beta^{-12}\right) \cdot(\alpha-\beta)^{24}}$ is equal to :