Rectangle
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. 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
oblong is occasionally used to refer to a non-square rectangle. A rectangle with vertices
ABCD would be denoted as
ABCD. The word rectangle comes from the Latin
rectangulus, which is a combination of
rectus and
angulus. A so-called
crossed rectangle is a crossed quadrilateral which consists of two opposite sides of a rectangle along with the two diagonals. It is a special case of an antiparallelogram, and its angles are not right angles. Other geometries, such as spherical, elliptic, and hyperbolic, have so-called rectangles with opposite sides equal in length and equal angles that are not right angles. Rectangles are involved in many tiling problems, such as tiling the plane by rectangles or tiling a rectangle by polygons.