Given a quadrilateral ABCD and the squares constructed externally on each side, then the two line segments between the centers of opposite squares are congruent and are perpendicular.

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Geometry Problems

Open Problems

Visual Index

Ten problems: 1411-1420

All Problems

Quadrilateral

Square

Triangle

Perpendicular lines

Congruence

Classical Theorems

Dynamic Geometry

van Aubel's theorem proof

GeoGebra

HTML5 and Dynamic Geometry

iPad Apps

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