MathNet 2015-part-04 — 191 problems (EN–VI) Question 17

Let $ABCDEF$ be a circumscribed hexagon. Let $AB \cap CD = K$, $CD \cap EF = L$, $DE \cap AF = M$ and $AF \cap BC = N$. Prove that the lines $KM$, $LN$ and $BE$ are concurrent.