MathDB
three circles

Source: 2003 Canadian Math Olympiad #4

September 19, 2011
ratiogeometry unsolvedgeometry

Problem Statement

Prove that when three circles share the same chord ABAB, every line through AA different from ABAB determines the same ratio XY:YZX Y : Y Z, where XX is an arbitrary point different from BB on the first circle while YY and ZZ are the points where AX intersects the other two circles (labeled so that YY is between XX and ZZ).