For \( \alpha, \beta, \gamma \ne 0 \), if \( \sin^{-1}\alpha+\sin^{-1}\beta+\sin^{-1}\gamma=\pi \) and \( (\alpha+\beta+\gamma)(\alpha-\gamma+\beta)=3\alpha\beta \), then \( \gamma \) equals:
\( \sqrt{3} \)
\( \dfrac{\sqrt{3}}{2} \)
\( \dfrac{1}{\sqrt{2}} \)
\( \dfrac{\sqrt{3}-1}{2\sqrt{2}} \)