Circle - Cyclic Quadrilateral

source: http://www.artofproblemsolving.com/

A cyclic quadrilateral is a quadrilateral that can be inscribed in a circle. They have a number of interesting properties.

Properties

In cyclic quadrilateral :

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Applicable Theorems/Formulae

The following theorems and formulae apply to cyclic quadrilaterals:

• Ptolemy's Theorem
• Brahmagupta's formula

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