MathDB

5

Part of 2016 Korea National Olympiad

Problems(1)

Perpendicularity in the Incircle Chord Lemma

Source: 2016 KMO Senior #5

11/12/2016
A non-isosceles triangle △ABC\triangle ABC has incenter II and the incircle hits BC,CA,ABBC, CA, AB at D,E,FD, E, F. Let EFEF hit the circumcircle of CEICEI at P≠EP \not= E. Prove that △ABC=2△ABP\triangle ABC = 2 \triangle ABP.
geometryincentercircumcircle