Fig. P$3\mathrm{.}5$ and P$3\mathrm{.}6$

$3\mathrm{.}6$ A $400-N$ force $P$ is applied at point $A$ of the bell crank shown.

$($a$)$ Compute the moment of the force $P$ about $O$ by resolving it into components

along line $OA$ and in a direction perpendicular to that line. $($b$)$ Determine the

magnitude and direction of the smallest force $Q$ applied at $B$ which has the same

moment as P about $O.$