# If $\theta$ is the angle between any two vectors $\overrightarrow{a} and \overrightarrow{b} ,$ then $|\overrightarrow{a}.\overrightarrow{b} | = | \overrightarrow{a} \times \overrightarrow{b} |$ when $\theta$ is equal to
$\begin {array} {1 1} (A)\;0 \quad (B)\;\frac{\pi}{4} \quad (C)\;\frac{\pi}{2} \quad (d)\;\pi \end {array}$