26 Sep
2006
26 Sep
'06
6:25 p.m.
I'm afraid I have to withdraw the "Seven Circle Theorem" as a contender for this list. When I sat down to examine the proof, I realised it is actually the "Eight Circle Theorem", and ought to be rendered Let A,C,D be circles tangent to one circle P, and B,E,F circles tangent to another circle Q [which may coincide with P or not]. If A,B,C,D,E,F,A are tangent in consecutive pairs, then the lines AD, BE, CF meet in a common point. A proof via Laguerre transformations is essentially trivial. Sorry about that, Ed! --- WFL