Question
Let $\vec{a}$ and $\vec{b}$ be two unit vectors and $\alpha$ be the angle between them, then $\vec{a} + \vec{b}$ is a unit vector, if $\alpha =$
Let $\vec{a}$ and $\vec{b}$ be two unit vectors and $\alpha$ be the angle between them, then $\vec{a} + \vec{b}$ is a unit vector, if $\alpha =$