Perimeter and Area of Composite Figures Outcome: D6

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Perimeter and Area of Composite
FiguresOutcome D6 Calculate the areas of
composite figuresMATH 8 STEWART
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Composite Figure

• A figure that is made by combining triangles,
  quadrilaterals, semi-circles and other
  two-dimensional figures.

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Perimeter Is the distance around a figure
7 cm
5 cm
3 cm
?
7 cm
4 cm
4 cm
4.71 cm
P 7 cm
5 cm
7 cm
P 27.71 cm
The perimeter of a circle has a special name, It
is called the ______________, and is found using
either of these formulas
circumference
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Alice is putting a wallpaper border around her
bedroom. She must find the __________ of her
bedroom in order to purchase the correct amount
of border.
perimeter
12 ft
3 ft
?
4 ft
6.5 ft
?
3.5 ft
8 ft
P 8 ft
6.5 ft
12 ft
3 ft
4 ft
3.5 ft
Alice needs to purchase 37 feet of border.
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The area of a composite figure can be found by
adding or subtracting the areas of the simpler
figures that compose the composite figure.
Area of Rectangle
Area of Semi-Circle
Area of Triangle
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Joe has to mow the lawn of the field below, how
many square meters must he mow?
14 m
3 m
10 m
10 m
6 m
6 m
8 m
8 m
Area of Rectangle
Area of Semi-Circle
Area of Triangle
7
Detective LeRue must investigate a crime
committed at the local park. How many square
meters of ground must he cover when looking for
clues?
Total area 28 m2 16 m2 21 m2
65 square meters
Is there another way of finding this area?
Area 4 m x 7 m
Area 4 m x 4 m
4 m
3 m
3 m
Area 3 m x 7 m
4 m
28 m2
7 m
7 m
21 m2
16 m2
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• Step 1 Find area of big rectangle

• Step 2 Find area of smaller rectangle

• Step 3 Subtract the smaller area from the
  larger area

Total area 77 m2 12 m2 65 square meters
How can we use subtraction to find the area?
11 m
4 m
3 m
4 m
3 m
Area 3 m x 4 m
4 m
7 m
7 m
Area 7 m x 11 m
12 m2
77 m2
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Detective LaRue must isolate the crime scene, how
much tape will he need?
Perimeter 7m 4 m 3 m 4 m 3 m 3 m
7 m 11 m
Detective LaRue needs 42 meters of crime scene
tape.
4 m
3 m
?
3 m
4 m
7 m
7 m
?
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1. Find the area and perimeter
6 cm
2 cm
5 cm
Area 79 cm2 Perimeter 40 cm
9 cm
5 cm
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2. Find the area and perimeter
Area 2300 in2 Perimeter 240 in
12
3. Find the area and perimeter
3 m
2 m
3 m
4.5 m
Area 30 m2 Perimeter 29 m
8 m
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4. Find the area and perimeter. Use 3.14
for p
Area 88.26 ft2 Perimeter 38.84 ft
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5. Find the area and perimeter
Area 212.75 km2 Perimeter 69.7 km
14 km
4 km
18 km
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6. Find the area and perimeter
Area 60 m2 Perimeter 36 m
3 m
12.5 m
7.5 m
13 m
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7. Find the area of the arrow.
Area 100 ft2
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8. Find the Area of the Shaded Region. Use
3.14 for p .
Area 437.5 mm2