Calculating the Area and the Perimeter

The perimeter is the length of the outline of a shape. To find the perimeter of a rectangle or square you have to add the lengths of all the 4 sides. x is, in this case, the length of the rectangle while y is the width of the rectangle.

The perimeter, P, is:

P= x+x+y+y

P= 2x+2y

P= 2(x+y)

Example

Find the perimeter of this rectangle:

(in)

P= 7+7+4+4

P= 2⋅7+2⋅4

P= 2⋅(7+4)

P= 2⋅11

P= 22in


The area is the measurement of the surface of a shape. To find the area of a square or a rectangle you need to multiply the length and the width of a rectangle or a square.

Area, A, is x times y.

A= x⋅y


Example

Find the area of this square.

(in)

A= x⋅y

A= 5⋅5

A= 25in2


There are different units for perimeter and area The perimeter has the same units as the length of the sides of rectangle or square whereas the area’s unit is squared.