In Euclidean plane geometry
, a rectangle
is any quadrilateral
with four right angles
. It can also be defined as an equiangular quadrilateral, since equiangular means that all of its angles are equal (360°/4 = 90°). It can also be defined as a parallelogram containing a right angle. A rectangle with four sides of equal length is a square
. The term is occasionally used to refer to a non-square
rectangle. A rectangle with vertices ABCD
would be denoted as .