A
quadrilateral in which all the angles are right angles and all the sides are congruent.
Formulas
The perimeter
P of a square with side length
c is : [latex]P=4c[/latex].
The area
A of a square with side length
c is : [latex]A=c\times c[/latex]

The formula for calculating the radius
r of the circle circumscribed about a square is : [latex]r=\frac{c}{2}\sqrt{2}[/latex]
The formula for calculating the radius
r of the circle inscribed in a square is :[latex]r=\frac{c}{2}[/latex]