# For any vector $\overrightarrow a\:\:and\:\:\overrightarrow b$ the angle between $|\overrightarrow a|\overrightarrow b+|\overrightarrow b|\overrightarrow a$ and $|\overrightarrow a|\overrightarrow b-|\overrightarrow b|\overrightarrow a$ is ?
$\begin{array}{1 1} 0 \\ \large\frac{\pi}{4} \\ \large\frac{\pi}{3} \\ \large\frac{\pi}{2} \end{array}$