MathDB
Angle bisectors

Source: Iran MO 3rd round 2016 finals - Geometry P3

September 5, 2016
geometryangle bisectorIran

Problem Statement

Given triangle ABC\triangle ABC and let D,E,FD,E,F be the foot of angle bisectors of A,B,CA,B,C ,respectively. M,NM,N lie on EFEF such that AM=ANAM=AN. Let HH be the foot of AA-altitude on BCBC. Points K,LK,L lie on EFEF such that triangles AKL,HMN\triangle AKL, \triangle HMN are correspondingly similiar (with the given order of vertices) such that AK∦HMAK \not\parallel HM and AK∦HNAK \not\parallel HN.
Show that: DK=DLDK=DL