Problem

Source: Sharygin 2011 Final 8.7

Tags: geometry, Locus, Locus problems, right angle, axes



Let a point $M$ not lying on coordinates axes be given. Points $Q$ and $P$ move along $Y$ - and $X$-axis respectively so that angle $P M Q$ is always right. Find the locus of points symmetric to $M$ wrt $P Q$.