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Sharygin CR 2019 P14

Source: Sharygin CR 2019 P14 (Grade 9 - 10)

March 6, 2019
geometry

Problem Statement

Let the side ACAC of triangle ABCABC touch the incircle and the corresponding excircle at points KK and LL respectively. Let PP be the projection of the incenter onto the perpendicular bisector of ACAC. It is known that the tangents to the circumcircle of triangle BKLBKL at KK and LL meet on the circumcircle of ABCABC. Prove that the lines ABAB and BCBC touch the circumcircle of triangle PKLPKL.