cyclic quadrilaterals   2 videos

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  Cyclic Quadrilaterals and Parallel Lines in Circles

  Geometry Circles

  How to prove that opposite angles in a cyclic quadrilateral are congruent; how to prove that parallel lines create congruent arcs in a circle.

  inscribed angles cyclic quadrilaterals parallel lines alternate interior angles
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  Rectangle and Square Properties

  Geometry Polygons

  How to define a rectangle and a square.

  equiangular polygon congruent diagonals bisect regular quadrilateral angle bisectors