Poncelet Porism for Triangles
Source: 10th Brazilian Math Olympiad - Problem 4
December 27, 2017
Brazilian Math Olympiad 1988geometryporismPlane Geometrycirclesincirclecircumcircle
Problem Statement
Two triangles are circumscribed to a circumference. Show that if a circumference containing five of their vertices exists, then it will contain the sixth vertex too.