Monday, May 21, 2012

Pappu's Theorem

If A1, B1, and C1 are three points on a line, and A2 , B2 and C2 are three points on a second line.If A1B2 meets A2B1 at X, and A1C2 meets A2C1 at Y, and B1C2 meets B2C1 at Z, then X, Y, and Z are collinear (on a straight line).
This is a Java Applet created using GeoGebra from - it looks like you don't have Java installed, please go to

1 comment:

  1. Could you explain why the reflections of any point on a circumcircle of a triangle when reflected in the sides of that triangle always forms a straight line? We loved showing it using Geogebra but have yet to find a proof. Thanks