MathDB

2

Part of 2005 JBMO Shortlist

Problems(1)

isosceles trapezoid with 3 equal sides

Source: JBMO Shortlist 2005

10/13/2017
Let ABCDABCD be an isosceles trapezoid with AB=AD=BC,AB//CD,AB>CDAB=AD=BC, AB//CD, AB>CD. Let E=AC∩BDE= AC \cap BD and NN symmetric to BB wrt ACAC. Prove that the quadrilateral ANDEANDE is cyclic.
JBMOgeometrytrapezoid