Question 22
Let $ABCDE$ be a cyclic pentagon in which $|CD| = |DE|$. Let the diagonals $AD$ and $BE$ intersect at point $K$, and let the diagonals $AC$ and $BD$ intersect at point $L$. Prove that the lines $KL$ and $EC$ are parallel.
Math Olympiad Vault · MathNet 2012