Rule

Area of a Square

The area of a square equals its side length s squared.


A = s^2

This is the result of multiplying the width and length of the square, both of which measure s.

Square of side s

Proof

Consider the unit square, a square with side lengths of one unit. By the definition of area, the space inside the square is one square unit. Now, divide a square of some integer side length s into unit squares.
Square of side s divided in unit squares
Since the original square has a side length s, there are exactly s rows of unit squares, each containing s squares. This means that the total number of unit squares that make up the square is the product of s and s. Number of Unit Squares: s * s This expression can be written as a power of s. s * s = s^2 The area of the square A can be found by multiplying the number of unit squares by the area of one unit square, 1. A=s^2 * 1=s^2 The formula for the area of a square of side length s has been proven.


A = s^2

This result is still valid if s were any real number.

Exercises