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China Mathematical Olympiad 2020 Q2

Source: China Mathematical Olympiad 2020 Q2

November 26, 2019
geometry

Problem Statement

In triangle ABCABC, AB>AC.AB>AC. The bisector of BAC\angle BAC meets BCBC at D.D. PP is on line DA,DA, such that AA lies between PP and DD. PQPQ is tangent to (ABD)\odot(ABD) at Q.Q. PRPR is tangent to (ACD)\odot(ACD) at R.R. CQCQ meets BRBR at K.K. The line parallel to BCBC and passing through KK meets QD,AD,RDQD,AD,RD at E,L,F,E,L,F, respectively. Prove that EL=KF.EL=KF.