1. LESSON 31
Areas of Rectangles

2. A) Areas of Rectangles
Area is the amount of surface enclosed by the sides of a shape.
Area of a rectangle = length times width
A = lw = bh
The units for your answers will be squares:
sq. cm (cm2), sq. ft (ft2), sq. in. (in.2)
Keep in mind that perimeter is the “line” that makes the shape (cm, ft, in.) while area is the surface inside the shape (cm2, ft2, in.2)

3. Practice (a-f)
Find the number of square units needed to cover the area of these shapes: a) 6
A = bh
= 6(4)
= 24 sq. units 4 7 b)
(a-f)
A = bh
= 7(7)
= 49 units2

4. c) A = bh = 8(5) = 40 sq. mm A = bh = 12(12) = 144 mm2 8 mm 5 mm 12 mmd)
A = bh
= 12(12)
= 144 mm2

5. The area of a square is 25 square inches.
e) How long is each side of the square?
What number times itself is 25? 5
So each side of the square is 5 inches.
(This is the square root of the area.)
f) What is the perimeter of the square?
P =
= 20 inches