Learn to find the area of rectangles and other parallelograms.

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Learn to find the area of rectangles and other
parallelograms.
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Insert Lesson Title Here
Vocabulary
area
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The area of a figure is the number of unit
squares needed to cover the figure. Area is
measured in square units.
AREA OF A RECTANGLE
The area A of a rectangle is the product of its
length l and its width w.
w
A lw
l
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Additional Example 1 Finding the Area of a
Rectangle
Find the area of the rectangle.
4.5 in.
7.4 in.
A lw
Use the formula.
A 7.4 4.5
Substitute for l and w.
Multiply.
A 33.3
The area of the rectangle is 33.3 in2.
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Try This Example 1
Find the area of the rectangle.
6.3 in.
8.2 in.
A lw
Use the formula.
A 8.2 6.3
Substitute for l and w.
Multiply.
A 51.66
The area of the rectangle is 51.66 in2.
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For any parallelogram that is not a rectangle,
you can cut a right triangle-shaped piece from
one side and move it to the other side to form a
rectangle.
The base of a parallelogram is the length of one
side. The height of a parallelogram is the
perpendicular distance from the base to the
opposite side.
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The area A of a parallelogram is the product of
its base b and its height h.
A bh
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Additional Example 2 Finding the Area of a
Parallelogram
Find the area of the parallelogram.
A bh



A 16
8
8 m

A 128
16 m
The area of the parallelogram is 128 m2.
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Try This Example 2
Find the area of the parallelogram.
A bh



A 12
6
6 cm
A 72
12 cm
The area of the parallelogram is 72 cm2.
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Additional Example 3 Measurement Application
A carpenter is using 2-ft by 2-ft square tiles to
cover a rectangular floor. If the area of the
floor is 150 ft2, what is the least number of
tiles the carpenter will need?
First find the area of each tile.
A lw
Use the formula for the area of a square.
A 2 2
Substitute 2 for l and 2 for w.
A 4
Multiply.
The area of each square tile is 4 ft2.
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Additional Example 3 Continued
To find the number of tiles needed, divide the
area of the floor by the area of one tile.
150 ft2 4 ft2
37.5
Since covering the floor requires more than 37
tiles, the carpenter would need at least 38 tiles.
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Insert Lesson Title Here
Try This Example 3
Amanda decided to use 1.5-ft by 1.5-ft square
tiles to cover a rectangular floor. If the area
of the floor is 200 ft2, what is the least number
of tiles Amanda will need?
First find the area of each tile.
A lw
Use the formula for the area of a square.
A 1.5 1.5
Substitute 1.5 for l and 1.5 for w.
A 2.25
Multiply.
The area of each square tile is 2.25 ft2.
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Try This Example 3 Continued
To find the number of tiles needed, divide the
area of the floor by the area of one tile.
200 ft2 2.25 ft2
88.9
Since covering the floor requires more than 88
tiles, Amanda would need at least 89 tiles.
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Insert Lesson Title Here
Lesson Quiz Part 1
Find the area of each figure. 1.
2. 3.
1 2
3.5 ft
2
ft
7 ft
24.5 ft2
1 4
ft
5
4.
7 ft
1 2
4
84 ft2
12 ft
1 2
6
ft
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Insert Lesson Title Here
Lesson Quiz Part 2
5. Suzanne is planning to use 1 ft by 0.5 ft
tiles to finish her bathroom floor. If her floor
is 7 ft by 10 ft, how many tiles will she need?

140 tiles