Question

theorem of cyclic quadrilateral
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Answer 1

Answer:

Theorem 2: The ratio between the diagonals and the sides is special and is known as Cyclic quadrilateral theorem. If there's a quadrilateral which is inscribed in a circle, then the product of the diagonals is equal to the sum of the product of its two pairs of opposite sides.

Answer 2

Theorem 1: In a cyclic quadrilateral, the sum of either pair of opposite angles is supplementary.