Mathematics

Problem

If vectors

\mathbf{a}

and

\mathbf{b}

are non-collinear, then

\frac{\mathbf{a}}{|\mathbf{a}|} + \frac{\mathbf{b}}{|\mathbf{b}|}

is a. a unit vector b. in the plane of

\mathbf{a}

and

\mathbf{b}

c. equally inclined to

\mathbf{a}

and

\mathbf{b}

d. perpendicular to

\mathbf{a} \times \mathbf{b}