Geometry Area of Composite Figures-1

Report
Take out a calculator to
try to solve the following
problems on area of
composite figures.
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For Learning to Happen!
•Pay close attention to this lesson.
•This lesson is very short.
•However, this is a challenging lesson!
•It is important to follow along with the slides
so that you know how to do you know how to
calculate the area of composite figures!
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To understand
COMPOSITE FIGURES
you first must know
how to calculate
missing sides.
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What are the missing side lengths?
12 m – 9 m =
3m
9m
6m
3m
12 m
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What are the missing side lengths?
6m –3m=
3m
3m
6m
9m
3m
12 m
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What are the missing side lengths?
3 ft
10 ft – 7 ft = 3 ft
7 ft
10 ft
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What are the missing side lengths?
1 in
5 in + 3 in + 2 in + 1 in = 11 in
2 in
14 in – 11 in =
3 in
3 in
5 in
14 in
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There are multiple
methods for solving Area
of Composite Figures.
st
The 1 method I am
going to show you is
how to break it up into
simpler area problems.
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What is the total shaded area?
Area1 A  s
2
3  9
3m
6m
2
3m
9m
12 m

3 m Area 2 A  bh
 12  3
Total Area
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 36

45 m
2
nd
2
The
method involves
finding an entire area
and then subtracting
smaller areas.
Pay attention you don’t
want to miss this!
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What is the total shaded area?
3m
Area1
3m
6m
9m
12 m

= l·w
6  12  72 m2
3 m Area 2 = l · w
2
9  3  27 m
=
Total Area
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 45 m2
Find the perimeter of the figure below.
10
8
Perimeter
4
4
8
6
8 +16 +8 +10 +4 +6 +4
= 56 UNITS
16
16 – 6 = 10
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Find the area of the figure below.
Area
10
Area1  l  w
4
8
4
6
16
8
-
16 · 8 = 128 un
Area 2  l  w
=
Total
Area
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6 · 4 = 24 un
2
2
= 104 un
2
Find the area of the figure below.
12- 5 = 7ft
Subtract the area of the
triangle from the area of
the rectangle.
Area of the rectangle:
A = bh
A = 12
•
9=
108
9 ft
5 ft
6 ft
12 ft
Area of the triangle:
1
__
A = bh
2
1
ft2 A = __
• (6)(7)
2
1
__
A=
• 42 =
2
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21 ft2
Find the area of the figure below.
12- 5 = 7ft
Shaded area=
Area of the rectangle
– Area of the triangle
A=
9 ft
108 – 21 = 87 ft2
Area of the rectangle:
A = bh
A = 12
•
9=
108
5 ft
6 ft
12 ft
Area of the triangle:
1
__
A = bh
2
1
ft2 A = __
• (6)(7)
2
1
__
A=
• 42 =
2
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21 ft2
THE END!!!
Take out your study guide!
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#10
Area
20 m
13 m
5m
12 m
25m
Perimeter
Area1 = l · w
2
20  12  240 m
+
b

h
Area 2  2
5  12  30 m2
P = 12 + 20 + 13 + 25
2
2
P = 70 m
Total Area
 270 m
=
ANOTHER WAY: Area of a Trapezoid
A = (b1 + b2) x h
2
12(25  20)

2
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 270m
2

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