Homework

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Homework
Find the surface area of each figure to the
nearest tenth. Use 3.14 for p. 1. the cone
Find the surface area of each sphere, both in
terms of ? and to the nearest tenth. Use 3.14 for
p.
2. r 22 in
3. d 1.5 mi
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Warm Up A cylindrical can has a diameter of 14
cm and a height of 20 cm. What is the surface
area to the nearest tenth? Use 3.14 for ?.
1186.9 cm2
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Vocabulary
slant height right cone great circle
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The slant height of a cone is measured along its
lateral surface.
Right cone
In a right cone, a line perpendicular to the base
through the vertex passes through the center of
the base.
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Check It Out! Example 1
Find the surface area of each figure to the
nearest tenth. Use 3.14 for p.
S pr2 prl
18 ft
p(72) p(7)(18)
7 ft
175p ? 549.5 ft2
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A sphere is the set of points in three dimensions
that are a fixed distance from a given point, the
center. A plane that intersects a sphere through
its center divides the sphere into two halves or
hemispheres. The edge of a hemisphere is a great
circle.
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The surface area of a sphere is four times the
area of a great circle.
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Additional Example 2 Finding Surface Area of a
Sphere
Find the surface area, both in terms of p and to
the nearest tenth. Use 3.14 for p.
Surface area of a sphere
S 4pr2
4p(32)
Substitute 3 for r.
36p in2 ? 113.0 in2
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Check It Out! Example 2
The moon has a radius of 1738 km. Find the
surface area, both in terms of p and to the
nearest tenth. Use 3.14 for p.
S 4pr2
Surface area of a sphere
4p(17382)
Substitute 1738 for r.
12,082,576p km2 ? 37,939,288.6 km2
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Homework Solutions
Find the surface area of each figure to the
nearest tenth. Use 3.14 for p. 1. the cone
175.8 in2
Find the surface area of each sphere, both in
terms of ? and to the nearest tenth. Use 3.14 for
p.
2. r 22 in
1936p in2, 6079.0 in2
3. d 1.5 mi
2.25p mi2, 7.1 mi2