Warm Up

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Warm Up
Problem of the Day
Lesson Presentation
Lesson Quizzes
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Warm Up Find the perimeter or circumference of
each figure. Use 3.14 for ?. 1. 2.
30 cm
138.16 ft
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Problem of the Day In a survey, 69 people were
asked whether they prefer hamburgers or hot dogs.
Thirty-three people said they prefer hot dogs.
What percent of the people surveyed said they
prefer hamburgers?
about 52
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Sunshine State Standards
MA.7.G.2.1 Justify and apply formulas for surface
area..ofpyramidsand cones. Also MA.7.G.2.2
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Vocabulary
regular pyramid slant height of a pyramid slant
height of a cone
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The base of a regular pyramid is a regular
polygon, and the faces are congruent isosceles
triangles.
The diagram shows a square pyramid. The blue
dashed line labeled l is the slant height of the
pyramid, the distance from the vertex to the
midpoint of an edge of the base.
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Additional Example 1A Finding the Surface Area
of a Pyramid
Find the surface area of the pyramid.
1 2
S B Pl
Use the formula.
B lw
Substitute. P 4(9) 36
S 81 180
Add.
S 261 m2
The surface area is 261 square meters.
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Additional Example 1B Finding the Surface Area
of a Pyramid
Find the surface area of the pyramid.
1 2
S B Pl
Use the formula.
B ½bh.
S 62.28 108
S 170.28
The surface area is 170.28 m2.
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Check It Out Example 1A
Find the surface area of each pyramid.
S 49 168 217
217 mm2
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Check It Out Example 1B
Find the surface area of the pyramid
1 2
1 2
S B Pl
B (8)(6.9) 27.6
S 94.8
94.8 m2
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The diagram shows a cone and its net. The blue
dashed line is the slant height of the cone, the
distance from the vertex to a point on the edge
of the base.
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Additional Example 2 Finding the Surface Area of
a Cone
Find the surface area of the cone. Use 3.14 for ?.
S ?r2 ?rl
Use the formula.
S (3.14)(32) (3.14)(3)(10)?
Substitute.
S 28.26 94.2
Multiply.
S 122.46
Add.
The surface area is about 122.46 square
centimeters.
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Check It Out Example 2A
Find the surface area of the cone. Use 3.14 for ?.
S ?r2 ?rl 3.14(2)2 3.14 (2)(8)
S 12.56 50.24?
S 62.8 ft2
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Check It Out Example 2B
The dimensions of the cone from Exercise 2a
quadrupled. Find the surface area of the cone.
Use 3.14 for ?.
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Lesson Quizzes
Standard Lesson Quiz
Lesson Quiz for Student Response Systems
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Lesson Quiz
1. Find the surface area of the pyramid. 2. Find
the surface area of the cone. Use 3.14 for ?.
236.25 m2
219.8 ft2
3. A house being built is to have a roof in the
shape of a square pyramid. The sides of the
square base are 21 feet long and the slant height
will be 12 feet. What will the surface area of
the roof be? (Hint The base of the pyramid is
not part of the roof.)?
504 ft²
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Lesson Quiz for Student Response Systems
1. Find the surface area of a regular pyramid
with a base of 12 feet by 12 feet and a slant
height of 14 feet. A. 2016 ft2 B. 816
ft2 C. 480 ft2 D. 240 ft2
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Lesson Quiz for Student Response Systems
2. Find the surface area of a cone with a radius
of 3 feet and a slant height of 6 feet. Use 3.14
for ?. A. 18 ft2 B. 56.52 ft2 C.
75.36 ft2 D. 84.78 ft2