Square (geometry)

Square
A regular quadrilateral (tetragon)
Type	Regular polygon
Edges and vertices	4
Schläfli symbol	{4}
Coxeter diagram
Symmetry group	Dihedral (D4), order 2×4
Internal angle (degrees)	90°
Dual polygon	Self
Properties	Convex, cyclic, equilateral, isogonal, isotoxal

In geometry, a square is a regular quadrilateral, which means that it has four equal sides and four equal angles (90-degree angles, or right angles). It can also be defined as a rectangle in which two adjacent sides have equal length. A square with vertices ABCD would be denoted ${\displaystyle \square }$ ABCD.

A square is a special case of a rhombus (equal sides, opposite equal angles), a kite (two pairs of adjacent equal sides), a parallelogram (opposite sides parallel), a quadrilateral or tetragon (four-sided polygon), and a rectangle (opposite sides equal, right-angles) and therefore has all the properties of all these shapes, namely:

The perimeter of a square whose four sides have length ${\displaystyle \ell }$ is