<BXD - <BYD = <BSD if <AXC - <AYC = <ASC, trapezoid ABCD
Source: 2021 Sharygin Geometry Olympiad Finals grades X-XI p6
August 2, 2021
geometrytrapezoidanglesequa angles
Problem Statement
The lateral sidelines and of trapezoid meet at point . The bisector of angle meets the bases of the trapezoid at points and ( lies inside segment ). Point is chosen on segment , and point is selected on the extension of beyond such a way that . Prove that .