For two vectors $\vec{a}$ and $\vec{b}$ Assertion (A) : $|\vec{a} imes \vec{b}|^2 + $\vec{a} \cdot \vec{b}$^2 = |\vec{a}|^2 |\vec{b}|^2$ Reason (R) : $|\vec{a} imes \vec{b}| = $\vec{a} \cdot \vec{b}$ an heta, \left$ heta eq \frac{\pi}{2} ight$$