MathDB
intersection of two circles

Source: Iranian third round 2015 geometry problem 1

September 10, 2015
geometrytrapezoidcircumcircle

Problem Statement

Let ABCDABCD be the trapezoid such that AB∥CDAB\parallel CD. Let EE be an arbitrary point on ACAC. point FF lies on BDBD such that BE∥CFBE\parallel CF. Prove that circumcircles of △ABF,△BED\triangle ABF,\triangle BED and the line ACAC are concurrent.
Back to ProblemsView on AoPS