MathDB
concyclic

Source: Polish MO Second Round 1960 p5

August 31, 2024
geometryConcyclic

Problem Statement

There are three different points on the line A A , B B , C C and a point S S outside this line; perpendicularly drawn at points A A , B B , C C to the lines SA SA , SB SB , SC SC intersect at points M M , N N , P P . Prove that the points M M , N N , P P , S S lie on the circle