Question 73
Let $ABC$ be an acute triangle with $AB \lt BC$, $O$ the center of its circumscribed circle and $B'$ the foot of the altitude from $B$. The parallel through $B'$ to $CO$ meets the line $BO$ at the point $X$. Show that $X$ and the midpoints of the segments $[AB]$ and $[AC]$ are collinear.