AT bisects BC
Source: 2021 China Second Round A2 , additional test, p1
April 29, 2024
geometrybisects segment
Problem Statement
As shown in the figure, in the acute angle , , is the midpoint of the minor arc of the circumcircle of . is the intersection point of the bisector of the exterior angle and the extension line of . From point draw a line perpendicular on and take a point (different from ) on that line , such that . Let the circumscribed circle of intersect the circle at point and at another point . Prove that bisects line segment .
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