quadrilateral
A quadrilateral![]()
is a four-sided polygon
![]()
.
Very special kinds of quadrilaterals are parallelograms![]()
(squares, rhombuses, rectangles
![]()
, etc.), although cyclic quadrilaterals
![]()
are also interesting on their own.Notice however, that there are quadrilaterals that are neither parallelograms nor cyclic quadrilaterals.