MathDB
collinear, 2 squares and isosceles (2019 Novosibirsk Oral Geo Oly 7.4)

Source:

April 26, 2021
geometrySquaresisoscelescollinear

Problem Statement

Two squares and an isosceles triangle are positioned as shown in the figure (the up left vertex of the large square lies on the side of the triangle). Prove that points A,BA, B and CC are collinear. https://cdn.artofproblemsolving.com/attachments/d/c/03515e40f74ced1f8243c11b3e610ef92137ac.png