Difference between revisions of "Cyclic quadrilateral"

(wiki-fied, added properties)
m (Cyclic Quadrilateral moved to Cyclic quadrilateral: removed unnecessary capitalization)
(No difference)

Revision as of 19:23, 18 June 2006

Cyclic Quadrilaterals are quadrilaterals that can be inscribed in circles. They occur frequently on math contests and olympiads due to their interesting properties.


In cyclic quadrilateral $ABCD$:

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

Applicable Theorems/Formulae

The following theorems and formulae apply to cyclic quadrilaterals:

Invalid username
Login to AoPS