The Perspective Centers of
the Tangential and Contact Triangles of the
inner and outer Soddy Points. The Rigby points are given by

where is the Incenter and

**References**

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

© 1996-9

1999-05-25