Answer
$P$ = -5$\sqrt2$,-5$\sqrt2$)
Work Step by Step
The Point $P$ is represented by the coordinate ($x$,$y$).
$\cos$ $\theta$ = $\frac{x}{r}$
$\cos$ 225$^{\circ}$ = $\frac{x}{10}$
x = 10 $\cos$ 225$^{\circ}$
x = 10(-$\frac{\sqrt2}{2}$)
x = -5$\sqrt2$
$\sin$ $\theta$ = $\frac{y}{r}$
$\sin$ 225$^{\circ}$ = $\frac{y}{10}$
y = 10 $\sin$ 225$^{\circ}$
y = 20(-$\frac{\sqrt2}{2}$)
y = -5$\sqrt2$
Therefore:
$P$ = -5$\sqrt2$,-5$\sqrt2$)