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2a

Part of 2011 Abels Math Contest (Norwegian MO)

Problems(1)

perpendicular diagonals wanted in a ABCD given sidelengths

Source: Norwegian Mathematical Olympiad 2011 - Abel Competition p2a

9/4/2019
In the quadrilateral ABCDABCD the side ABAB has length 7,BC7, BC length 14,CD14, CD length 2626, and DADA length 2323. Show that the diagonals are perpendicular.
You may assume that the quadrilateral is convex (all internal angles are less than 180o180^o).
geometryperpendiculardiagonalssidelengths