Question 109
Circles $j$ and $k$, centered at $O$ and $P$ respectively, do not intersect. The two tangent rays from $O$ to $k$ meet $j$ at $A$ and $B$, respectively, and the two tangent rays from $P$ to $j$ meet $k$ at $C$ and $D$, respectively. Prove that $A, B, C$, and $D$ are the vertices of a rectangle.
