The Radical Lines of three Circles are Concurrent in a point known as the radical center (also called the Power Center). This theorem was originally demonstrated by Monge (Dörrie 1965, p. 153).

**References**

Dörrie, H. *100 Great Problems of Elementary Mathematics: Their History and Solutions.* New York: Dover, 1965.

Johnson, R. A. *Modern Geometry: An Elementary Treatise on the Geometry of the Triangle and the Circle.* Boston, MA:
Houghton Mifflin, p. 32, 1929.

© 1996-9

1999-05-25