From - Tue Jun 1 10:45:09 1999 From: xpolakis@hol.gr (Antreas P. Hatzipolakis) Newsgroups: rec.puzzles,sci.math Subject: Re: Trisecting a line Date: 30 May 1999 19:36:57 GMT Organization: Crete Lines: 27 Message-ID: In article <7iot2q$q27$1@news.fas.harvard.edu>, Noam D. Elkies wrote (in part): > [I found this myself some 20 years ago, but imagine that it's a And some 10 years ago I read this problem by Noam D. Elkies: For plane triangle A_1A_2A_3, call two circles within the triangle companion incircles if they are the incircles of two triangles formed by dividing A_1A_2A_3 into two smaller triangles by passing a line through one of the vertices and some point on the opposite side. (a) Show that any chain of circles C_1,C_2,.... such that C_i, C_i+1 are companion incircles for every i consists of at most six distinct circles. (b) Give a ruler and compass construction for the unique chain which has only three distinct circles. (c) For such a chain of three circles show that the three subdividing lines are concurrent. I guess he (:the problem's author) is you, unless it was written by another man of that name cf. Actually, Homer was not written by Homer but by another man of that name. :-)) Antreas