Problem

Source: Olimphíada 2023 - Problem 2/Level 3

Tags: geometry, Isogonal conjugate, circumscribed quadrilateral



Let $ABCD$ be a quadrilateral circumscribed around a circle $\omega$ with center $I$. Assume $P$ and $Q$ are distinct points and are isogonal conjugates such that $P, Q$, and $I$ are collinear. Show that $ABCD$ is a kite, that is, it has two disjoint pairs of consecutive equal sides.