9-point Circle as a Locus of Concurrency:
What Is This About?
A Mathematical Droodle
5 November 2015, Created with GeoGebra
The applet illustrates a theorem published in 1857 by Griffiths:
If a point moves on a fixed line through the circumcenter, its pedal circle passes through a fixed point on the nine point circle.
Copyright © 1996-2018 Alexander Bogomolny