MathDB
Parallelograms for a rectangle

Source:

June 8, 2008
geometryparallelogramrectanglegeometry proposed

Problem Statement

Let ABCD ABCD be a convex cuadrilateral inscribed in a circumference centered at O O such that AC AC is a diameter. Pararellograms DAOE DAOE and BCOF BCOF are constructed. Show that if E E and F F lie on the circumference then ABCD ABCD is a rectangle.
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