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NMTC JUNIOR 2023 FINALS P2

Source: NMTC 2023 P2 (JUNIOR)

November 5, 2023
geometrycircumcirclenmtc

Problem Statement

PQRPQR is an acute scalene triangle. The altitude PLPL and the bisector RKRK of QRP\angle QRP meet at HH (LL on QRQR and KK on PQPQ). KMKM is the altitude of triangle PKRPKR; it meets PLPL at NN. The circumcircle of NKR\triangle NKR meets QRQR at SS other than QQ. Prove that SHKSHK is an isosceles triangle.