MathDB
circumcircles are vertices of an equilateral triangle, right triangle wanted

Source: Tuymaada 2000 Juniors 6

April 28, 2019
geometrycircumcircleright triangleSquares

Problem Statement

Let OO be the center of the circle circumscribed around the the triangle ABCABC. The centers of the circles circumscribed around the squares OAB,OBC,OCAOAB,OBC,OCA lie at the vertices of a regular triangle. Prove that the triangle ABCABC is right.