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A line, a median and a bisector have a common point

Source: Tuymaada 2014, Day 2, Problem 3, Senior League

July 12, 2014
geometryparallelogramincenteranalytic geometrygeometry unsolvedTuymaada

Problem Statement

A parallelogram ABCDABCD is given. The excircle of triangle ABC\triangle{ABC} touches the sides ABAB at LL and the extension of BCBC at KK. The line DKDK meets the diagonal ACAC at point XX; the line BXBX meets the median CC1CC_1 of trianlge ABC\triangle{ABC} at Y{Y}. Prove that the line YLYL, median BB1BB_1 of triangle ABC\triangle{ABC} and its bisector CCCC^\prime have a common point.
(A. Golovanov)