1.22: Past-paper question 3

Referred (3i (a) Find, respectively. to as a a fixed simplified origin expression the position in terms vectors of i and of the points $\displaystyle P$ and $\displaystyle Q$ are (5i $\displaystyle + 6j)$ and

(b) Find a unit vector parallel to $\displaystyle {\overline{{P Q}}}.$

The Given position that vector of the fixed point $\displaystyle R$ is (13i $\displaystyle +$ aj), where a is a constant.

(c) find the value of a.