MathDB
collinearity wanted, 2 squares related

Source: 2023 NZMO - New Zealand Maths Olympiad Round 2 p3

September 2, 2023
geometrycollinear

Problem Statement

Let ABCDABCD be a square (vertices labelled in clockwise order). Let ZZ be any point on diagonal ACAC between AA and CC such that AZ>ZCAZ > ZC. Points XX and YY exist such that AXYZAXY Z is a square (vertices labelled in clockwise order) and point BB lies inside AXYZAXY Z. Let MM be the point of intersection of lines BXBX and DZDZ (extended if necessary). Prove that CC, MM and YY are colinear