The Lesson

A square is a four sided shape with four equal sides and four right angles.

a square

Dictionary Definition

The Oxford English Dictionary defines a rectangle as "a plane rectilinear and rectangular figure with four equal sides."
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Properties of Squares

  • All sides of a square are of equal length.

    all sides of a square are of an equal length
  • All angles in a square are right angles.

    all angles in a square are right angles
  • Opposite sides of a square are parallel.

    opposite sides of a square are parallel
  • All angles of a square add up to 360°.

    angles in a square add up to 360 degrees
  • The diagonals of a square bisect each other at right angles. The diagonals cross each other half-way along their lengths and are perpendicular to each other.

    diagonals of a square bisect each other

The Perimeter of a Square

The perimeter of a square is given by the formula:

perimeter of a square equals four times the side length In this formula, a is the length of the side of the square.

The Area of a Square

The area of a square is given by the formula:

area of a square equals side length squares In this formula, a is the length of the side of the square.
Read more about how to find the area of a square

Interactive Widget

Here is an interactive widget to help you learn about squares.

A Square is a Polygon

A square is a type of polygon. A polygon is a 2-dimensional shape with straight sides. A square is a regular polygon. Regular polygons have the same length sides and the same angles.

A Square Is a Quadrilateral

A square is a quadrilateral. A square is a four-sided polygon. Parallelograms, rectangles and trapezoids are also quadrilaterals.

Square Numbers...

A square number is a number multiplied by itself.

12 = 1 × 1 = 1

22 = 2 × 2 = 4

32 = 3 × 3 = 9

The squares go 1, 4, 9... A square with side length 1 has an area of 1.

a square with side length 1 has an area of 1 A square with side length 2 has an area of 4.

a square with side length 2 has an area of 4 A square with side length 3 has an area of 9.

a square with side length 3 has an area of 9 The areas go 1, 4, 9... The square of a number and the area of a square with side lengths of that number are the same.

...and Square Roots

A square root is the inverse of a square number. If a number represented the area of a square, then the square root represents the length of the side of that square.