MathDB
Median geo

Source: St. Petersburg 2023 9.3

August 12, 2023
geometry

Problem Statement

Let MM be the midpoint of ACAC in an acute triangle ABCABC. Let KK be a point on the minor arc ACAC, such that AKM=90o\angle AKM=90^{o}. Let BKAM=XBK \cap AM=X and the AA-altitude meets BMBM at YY. Show that XYABXY \parallel AB.