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