Problem

The incident ray, reflected ray and the outward drawn normal are denoted by the unit vectors

\vec{a}

\vec{b}

and

\vec{c}

respectively. Then choose the correct relation for these vectors. a.

\vec{b} = 2\vec{a} + \vec{c}

\vec{b} = \vec{a} - \vec{c}

\vec{b} = \vec{a} + 2\vec{c}

\vec{b} = \vec{a} - 2(\vec{a} \cdot \vec{c})\vec{c}