4

Part of 1988 Brazil National Olympiad

Problems(1)

Poncelet Porism for Triangles

Source: 10th Brazilian Math Olympiad - Problem 4

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.

Brazilian Math Olympiad 1988geometryporismPlane Geometrycirclesincirclecircumcircle