Question 80
Let $H$ be the orthocenter of a triangle $ABC$, $M$ be the midpoint of $AB$, $N$ be the midpoint of $AC$. The rays $MH$ and $NH$ intersect the circumcircle of $ABC$ at points $P$ and $Q$ respectively. Prove that the lines $BQ$, $CP$ and $AH$ are either concurrent or parallel.