Maths Olympiad Prep

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Geometry Difficulty 4.8 AIME Prove it Italy

In a convex quadrilateral ABCDABCD the sides ABAB, BCBC, CDCD are equal. Moreover AC=BD=ADAC = BD = AD. What is the measure of the angle at DD?

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.