MathDB
easy geometry

Source: iranian TST second exam p2

June 3, 2015
geometryincentercircumcircle

Problem Statement

In triangle ABCABC(with incenter II) let the line parallel to BCBC from AA intersect circumcircle of ABC\triangle ABC at A1A_1 let AIBC=DAI\cap BC=D and EE is tangency point of incircle with BCBC let EA1(ADE)=T EA_1\cap \odot (\triangle ADE)=T prove that AI=TIAI=TI.