freeCodeCamp/guide/english/mathematics/area-of-a-square/index.md

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Area of a Square

Area of a Square

A square is a quadrilateral with identical sides.

The area of a square can be calculated either from the length of the side, or from the length of the diagonal.

Square

If the side a is known:

Formula1

If the diagonal d is known:

Formula2

The relationship between side a and diagonal d is:

Diagonal

Terminology

Diagonal - the distance from opposite corners of a square. The corners are 90-degrees.

Perimeter - the sum of the length of four sides in a square. The four sides are equal in a square.

Examples

  1. Given length of one side of square is 8 units:
   Area = 8 x 8 = 64 units2 
  1. Given area of a square is 100 units2:
 Length = 100 = 10 units 
  1. Given diagonal of square is 25 units:
 Area = 102 / 2 = 50 units2 
  1. Given perimeter of a square is 20 units:
 Area = (20 / 4)2 = 25  units2 

Find the area of a square given the perimeter:

To find the area of a square given the perimeter, simply start by dividing the given perimeter by 4. Why 4? Because a square has four (4) sides. Dividing it by 4 would give you the length of one side. Now square the known side. To square, multiply it by itself once. Once you get the result, convert it to squared units; by adding a ² to the answer.

Ex: Perimeter: 20

 20 / 4 = 5 
 5 x 5 = 25 
 25 = 25² 

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