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Cyclic quadrilateral

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

image:Cyclicquad2.png

Properties

In cyclic quadrilateral ABCD:

  • \angle A + \angle C = \angle B + \angle D = {180}^{o}
  • \angle ABD = \angle ACD
  • \angle BCA = \angle BDA
  • \angle BAC = \angle BDC
  • \angle CAD = \angle CBD

Applicable Theorems/Formulae

The following theorems and formulae apply to cyclic quadrilaterals:

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