Vector Algebra

If \(\alpha, \beta\) and \(\gamma\) are the angles between the vectors \(\overrightarrow{\mathrm{P}}, \overrightarrow{\mathrm{Q}}\), and \(\overrightarrow{\mathrm{R}}\) and \(\alpha=90^{\circ}\) as shown in figure. the product of \((\vec{Q} \times \vec{R}) \cdot \vec{Q}\) is equal to