An Angle Sum from Trisection Points

In right triangle $ABC$, $\angle C = 90^\circ$ and $AC : CB = 1 : 3$. Points $E$ and $D$ are the two trisection points of $CB$, with $E$ between $C$ and $D$. Let $\angle 1 = \angle ABC$ and $\angle 2 = \angle ADC$. Prove that $\angle 1 + \angle 2 = 45^\circ$.