Warm Up

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Warm Up
Problem of the Day
Lesson Presentation
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Warm Up 1. What is the area of a rectangle with
length 10 cm and width 4 cm? 2. What is the area
of a parallelogram with base 18 ft and height 12
ft? 3. What is the area of a triangle with base
16 cm and height 8 cm?
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Problem of the Day Four squares are stacked in a
tower. The bottom square is 12 inches on a side.
The perimeter of each of the other squares is
half of the one below it. What is the perimeter
of the combined figure?
69 in.
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Learn to break a polygon into simpler parts to
find its area.
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Additional Example 1A Finding Areas of Composite
Figures Find the area of the polygon.
Think Break the polygon apart into rectangles.
Find the area of each rectangle.
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Additional Example 1A Continued
A lw
A lw
Write the formula for the area of a rectangle.
A 4.9 1.7
A 2.1 1.3
A 8.33
A 2.73
8.33 2.73 11.06
Add to find the total area.
The area of the polygon is 11.06 cm2.
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Additional Example 1B Finding Areas of Composite
Figures Find the area of the polygon.
Think Break the figure apart into a rectangle
and a triangle.
Find the area of each polygon.
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Additional Example 1B Continued
A lw
A 28 24
A 168
A 672
Add to find the total area of the polygon.
672 168 840
The area of the polygon is 840 ft2.
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Check It Out Example 1A Find the area of the
polygon.
1.9 cm
1.5 cm
5.5 cm
2 cm
3.4 cm
Think Break the polygon apart into rectangles.
Find the area of each rectangle.
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Check It Out Example 1A Continued
A lw
A lw
Write the formula for the area of a rectangle.
A 5.5 1.9
A 2 1.5
A 10.45
A 3
10.45 3 13.45
Add to find the total area.
The area of the polygon is 13.45 cm2.
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Check It Out Example 1B Find the area of the
polygon.
36 ft
20 ft
22 ft
Think Break the figure apart into a rectangle
and a triangle.
Find the area of each polygon.
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Check It Out Example 1B Continued
16 ft
20 ft
22 ft
22 ft
A lw
A 22 20
A 176
A 440
Add to find the total area of the polygon.
440 176 616
The area of the polygon is 616 ft2.
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Additional Example 2 Art Application Patrick
made a design. Use the coordinate grid to find
its area.
Think Divide the design into rectangles. Find
the area of each rectangle.
Rectangle 1






25
l 5, w 5 A 5 5 25
20
Rectangle 2
15
l 10, w 5 A 10 5 50
10
Rectangle 3
5
l 15, w 5 A 15 5 75
0
10
5
15
20
25
Rectangle 4
l 20, w 5 A 20 5 100
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Additional Example 2 Continued
Add the areas of the four rectangles to find the
total area of the design.
25 50 75 100 250 square units.
The area of the design is 250 square units.
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Check It Out Example 2 Lawanda made a design.
Use the coordinate grid to find its area.
Think Divide the design into rectangles. Find
the area of each rectangle.






Rectangle 1
25
20
l 5, w 10 A 5 10 50
1
15
2
Rectangle 2
10
3
l 5, w 15 A 5 15 75
5
0
10
5
15
Rectangle 3
20
25
l 5, w 10 A 5 10 50
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Check It Out Example 2 Continued
Add the areas of the three rectangles to find the
total area of the design.
50 75 50 175 square units.
The area of the design is 175 square units.
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Lesson Quiz
1. Find the area of the figure shown.
220 units2
2. Phillip designed a countertop. Use the
coordinate grid to find its area.
30 units2