Rectangle
A closed planar Quadrilateral with opposite sides of equal lengths 
and 
, and with four Right Angles. The Area of the rectangle is
and its Diagonals are of length
A Square is a degenerate rectangle with
.See also Golden Rectangle, Perfect Rectangle, Square
References
Beyer, W. H. (Ed.) CRC Standard Mathematical Tables, 28th ed. Boca Raton, FL: CRC Press, p. 122, 1987. Eppstein, D. ``Rectilinear Geometry.''http://www.ics.uci.edu/~eppstein/junkyard/rect.html.
- Orthocenter
- Orthocentric Coordinates
- Orthocentric Quadrilateral
- Orthocentric System
- Orthocupolarotunda
- Orthodrome
- Orthogonal Array
- Orthogonal Basis
- Orthogonal Circles
- Orthogonal Curves
- Orthogonal Functions
- Orthogonal Group
- Orthogonal Group Representations
- Orthogonality Condition
- Orthogonality Theorem
- Orthogonal Lines
- Orthogonal Matrix
- Orthogonal Polynomials
- Orthogonal Projection
- Orthogonal Rotation Group
- Orthogonal Tensors
- Orthogonal Transformation
- Orthogonal Vectors
- Orthographic Projection
- Orthologic