MathDB
M is the midpoint of AB, incircles of ACM, BCM

Source: Itamo 2013, problem 2

May 17, 2013
geometrygeometry proposed

Problem Statement

In triangle ABCABC, suppose we have a>ba> b, where a=BCa=BC and b=ACb=AC. Let MM be the midpoint of ABAB, and α,β\alpha, \beta are inscircles of the triangles ACMACM and BCMBCM respectively. Let then AA' and BB' be the points of tangency of α\alpha and β\beta on CMCM. Prove that AB=ab2A'B'=\frac{a - b}{2}.