Formulas for Perimeter and Area

PERIMETER OF A

SQUARE

P= 4sPerimeter equals four times the length of one side

AREA OF ASQUARE

A=s2

Area of a square equals the length of one side squared (times itself)

3 in.

3 in.

Area of a Square

A=s²

A= 3 in. * 3 in.

A=9 sq. in.

Perimeter of a Square

P=4s

P=4(3 in.)

P=12 in.

PERIMETER OF ARECTANGLE

P=2l+2w

Perimeter of a rectangle equals 2 times the length plus 2 times the width

AREA OF ARECTANGLE

A=lw

Area of a rectangle equals length times width

2 in.

3 in.

Perimeter of a RectangleP=2l+2wP=2(3 in.) + 2 (2in.)P=6 in. + 4 in.P=10 in.

Area of a RectangleA=lwA=3 in.(2 in.)A=6sq. in.

4 cm

2.5 cm

Find the perimeter and area of each figure.

8 in.

11 in.

5 in.

7 in.4 in.

4 in.

square

Find the perimeter and area of each figure. Show all work!

Now let’s try it when the measurement needs to change.

We need the area in square feet.

12 in.

12 in.

There are 2 methods 1. Convert first.

2. Convert after you have the area

Convert first.12 inches = 1 ftMultiply 1 times 1Area is 1 square foot.12 in.

12”

12”

12”

Convert 2nd.

12 times 12 = 144 square inches.

How many square inches are in a square foot?

How man inches across the top?

How many across the side?

If we draw all of the boxes there will be 144 sq. inches in 1 square ft.

We have divide square inches by 144 to get square feet!

18 inches

24 in.

What is the area in square feet?

6 ft.

9 ft

Find area in square yards.

100 cm.

250 cm.

Find area in square meters.

Hints:100 cm = 1 meter10,000 sq cm = 1 sq meter

Homework: problems below

1.Find the perimeter and area both in feet and yards for a rectangle with a length of 15 feet and a width of 9 feet.

2.Find the perimeter & area of a square that has a side of 24 inches. Give your answer in both inches and feet.

3.Find the perimeter and area of the following figure.

12 in.

12 in.9 in.

6 in.Don’t forget to show all work!