Question 154
Let $ABC$ be a triangle with $(O)$ as its circumcircle. Take $D$ on the minor arc $BC$ of $(O)$ and the tangent line from $D$ to $(O)$ that intersects $BC$, $CA$, $AB$ at $M$, $N$, $P$. Line $AM$ cuts $(O)$ again at $K$ and $BN$, $CP$ meet at $H$. Prove that $H$, $K$, $D$ are collinear.