# Cyclic Quadrilateral Ptolemy's Theorem Proof

The Theorem states that the product of the diagonals of a cyclic quadrilateral is equal to the sum of the products of opposite sides.

## Cyclic Quadrilateral Ptolemy's Theorem

The Theorem states that the product of the diagonals of a cyclic quadrilateral is equal to the sum of the products of opposite sides.

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The online proof of *Ptolemy's Theorem* is made easier here.