MathDB
easy geometry

Source: Iran MO 2018, second round, p1

April 26, 2018
Irangeometry

Problem Statement

Let PP be the intersection of ACAC and BDBD in isosceles trapezoid  ABCDABCD (AB∥CDAB\parallel CD , BC=ADBC=AD ) . The circumcircle of triangle ABPABP inersects BCBC for the second time at XX . Point YY lies on AXAX such that DY∥BCDY\parallel BC . Prove that YDA^=2.YCA^\hat {YDA} =2.\hat {YCA} .
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