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Italian Mathematical Olympiad

Geometry Difficulty 4.8 AIME Prove it Italy

In a convex quadrilateral $ABCD$ the sides $AB$ , $BC$ , $CD$ are equal. Moreover $AC = BD = AD$ . What is the measure of the angle at $D$ ?

Solution

$\overline{\text { SOLUTION }}$

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Source: MathNet, licensed CC-BY-4.0. Statement translated into English from it; metadata (topic, difficulty) added by this project.