Question 75
Two circles $k_{1}$ and $k_{2}$ intersect at the points $A$ and $C$. Let $B$ be the second intersection of $k_{1}$ with the tangent to $k_{2}$ at $A$, and let $D$ be the second intersection of $k_{2}$ with the tangent to $k_{1}$ at $C$. Show that $AD$ and $BC$ are parallel.