MathDB
XEY is fixed

Source: 2024 CTST P22

March 29, 2024
geometry2024 CTST

Problem Statement

ABCABC is an isosceles triangle, with AB=ACAB=AC. DD is a moving point such that AD∥BCAD\parallel BC, BD>CDBD>CD. Moving point EE is on the arc of BCBC in circumcircle of ABCABC not containing AA, such that EB<ECEB<EC. Ray BCBC contains point FF with ∠ADE=∠DFE\angle ADE=\angle DFE. If ray FDFD intersects ray BABA at XX, and intersects ray CACA at YY, prove that ∠XEY\angle XEY is a fixed angle.
Back to ProblemsView on AoPS