If $\theta $ is the angle between any two vectors $\vec{a}$ and $\vec{b}$, then $|\vec{a}.\vec{b}|=|\vec{a}×\vec{b}|$ for $\theta $ equal to ________.

$\pi $ 0 $\frac{\pi }{2}$ $\frac{\pi }{4}$

$\frac{\pi }{4}$