For each $\triangle O R S, O$ is the origin, $R$ is on the positive ray of the $x$ -axis and $\overline{P S}$ is the altitude from $S$ to $\overrightarrow{O R}$ . Find the exact coordinates of $R$ and $S .$ b. Find the exact area of $\triangle O R S .$
$O R=5, \mathrm{m} \angle R O S=\frac{\pi}{3}, O S=3$