Diagonals of a quadrilateral $ABCD$ are equal and meet at point $O$. The perpendicular bisectors to segments $AB$ and $CD$ meet at point $P$, and the perpendicular bisectors to $BC$ and $AD$ meet at point $Q$. Find angle $\angle POQ$. by A.Zaslavsky
Problem
Source: Sharygin Geometry Olympiad 2016 Final Round problem 7 grade 8
Tags: geometry, perpendicular bisector, diagonals