The Compendium Geometry is an eBook providing facts, formulas and explanations about geometry.

Rectangle and Square

A rectangle is a closed planar quadrilateral with opposite sides of equal lengths having four right angles. A square is a degenerate rectangle with all sides of equal lengths, a = b.

The following table lists the most important parameters of rectangles and squares:

  Rectangle Square
Circumference 2(a+b) 4a
Area ab a2
Diagonal a
Circumcircle Radius d/2 a/
Incircle Radius - a/2

The center of gravity G as well as the center of the circumcircle lie at the intersection of the diagonals. Note that a rectangle does not have an incircle. For a square the center of the incircle lies at the intersection of the diagonals, too.

Last Update: 2010-12-06