# 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 four 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:

$$P=7+7+4+4$$

$$P=2\cdot 7+2\cdot 4$$

$$P=2\cdot (7+4)$$

$$P=2\cdot 11$$

$$P=22in$$

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

Area, A, is x times y.

$$A=x\cdot y$$

**Example**

Find the area of this square.

$$A=x\cdot y$$

$$A=5\cdot 5$$

$$A=25in^{2}$$

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.

**Video lesson**

Calculate the perimeter and the area in feet