MathDB
Incentre, circumcentre and midpoints of AC,BC are concyclic

Source: Baltic Way 1999

December 23, 2010
geometryincenterangle bisectorgeometry proposed

Problem Statement

In a triangle ABCABC it is given that 2AB=AC+BC2AB=AC+BC. Prove that the incentre of ABC\triangle ABC, the circumcentre of ABC\triangle ABC, and the midpoints of ACAC and BCBC are concyclic.