Given three coins of possibly different sizes which are arranged so that each is tangent to the other two, find the coin which is tangent to the other three coins. The solution is the inner Soddy Circle.

**References**

Oldknow, A. ``The Euler-Gergonne-Soddy Triangle of a Triangle.'' *Amer. Math. Monthly* **103**, 319-329, 1996.

© 1996-9

1999-05-26