MathDB
<AMD=<AND wanted, starting with isosceles rapezoid

Source: Indonesia INAMO Shortlist 2008 G7

August 25, 2021
geometryequal anglestrapezoidisosceles

Problem Statement

Given an isosceles trapezoid ABCDABCD with base ABAB. The diagonals ACAC and BDBD intersect at point SS. Let MM the midpoint of BCBC and the bisector of the angle BSCBSC intersect BCBC at NN. Prove that ∠AMD=∠AND\angle AMD = \angle AND.
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