MathDB
Iran(3rd round)2009

Source: Problem 2 Geometry

September 13, 2009
geometrytrapezoidsymmetrygeometry unsolved

Problem Statement

2-There is given a trapezoid ABCD ABCD.We have the following properties: AD\parallel{}BC,DA \equal{} DB \equal{} DC,\angle BCD \equal{} 72^\circ. A point K K is taken on BD BD such that AD \equal{} AK,K \neq D.Let M M be the midpoint of CD CD.AM AM intersects BD BD at N N.PROVE BK \equal{} ND.
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