Feuerbach 9 Point Circle DemonstrationDrag the points A, B and C to see the circle change. The other 9 points shown are the midpoints of the sides of triangle ABC, the foot points of the altitudes, and the midpoints of the line segments from the vertices of triangle ABC to the orthocenter of the triangle. Feuerbach did not actually prove that these points all lie on a circle, but he still gets credit... ... created as my Valentines present to my niece. Jeff Morgan, Created with GeoGebra |