Answer
$315^\circ$ from $+x$-axis
Work Step by Step
1. Based on the given points, we have
$\vec v=\vec{P_1P_2}=(8\sqrt 2-3\sqrt 2)+(2\sqrt 2-7\sqrt 2)i=5\sqrt 2-5\sqrt 2i=10(\frac{\sqrt 2}{2}-\frac{\sqrt 2}{2}i)=10(cos315^\circ+i\ sin315^\circ)$
2. Thus the direction angle of $\vec v$ is $315^\circ$ from $+x$-axis.
