MathDB
Midpoint of two circumcentre

Source: Sharygin final round 2017

July 31, 2017
geometrycircumcircle

Problem Statement

If two circles intersect at A,BA,B and common tangents of them intesrsect circles at C,DC,Dif OaO_ais circumcentre of ACDACD and ObO_b is circumcentre of BCDBCD prove ABAB intersects OaObO_aO_b at its midpoint
Back to ProblemsView on AoPS