Draw three nonintersecting Circles in the plane, and the common tangent line for each pair of two. The points of intersection of the three pairs of tangent lines lie on a straight line.

**References**

Coxeter, H. S. M. ``The Problem of Apollonius.'' *Amer. Math. Monthly* **75**, 5-15, 1968.

Graham, L. A. Problem 62 in *Ingenious Mathematical Problems and Methods.* New York: Dover, 1959.
Ogilvy, C. S. *Excursions in Geometry.* New York: Dover, pp. 115-117, 1990.

Walker, W. ``Monge's Theorem in Many Dimensions.'' *Math. Gaz.* **60**, 185-188, 1976.

© 1996-9

1999-05-26