## Rectangle

A rectangle is defined as a quadrilateral where all four of its angles are right angles.

A square is a special kind of rectangle where all four sides have equal length.

The perimeter of a rectangle may be computed by adding up its respective sides. As an example, consider the following rectangle:

The above rectangle has a length of 5 units and width of 4 units. Consequently, adding the total number of units equals:

5 units + 4 units + 5 units + 4 units = 18 units

However, noting that we are adding the length and width twice, the perimeter of the rectangle may be written as:

5 units + 4 units + 5 units + 4 units = 18 units

However, noting that we are adding the length and width twice, the perimeter of the rectangle may be written as:

Perimeter (Rectangle) = 2 (Length + Width)