Opening

1
Opening

• On your notecard write down everything you know
  about Spheres, Volume and surface area

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Sphere Vocabulary

• Sphere
• the set of all points in space equidistant from a
  given point

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If you cut a sphere right down the middle you
would create two congruent halves called
HEMISPHERES.
You can think of the globe. The equator cuts the
earth into the northern and southern hemisphere.
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• Great Circle
• The cross section formed when you cut a sphere in
  half

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Surface Area of a Sphere

• The surface area S of a sphere is
• Where r is the radius of the sphere

How is this similar to the area of a circle?
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EXAMPLE 1
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EXAMPLE 2
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EXAMPLE 3
The circumference of a great circle of a sphere
is 25 inches. Find the surface area of the
sphere. (Round to the nearest tenths.)
25 in
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GUIDED PRACTICE
1. The diameter of a sphere is 40 feet. Find
the surface area of the sphere.
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GUIDED PRACTICE
2. The surface area of a sphere is 30p square
meters. Find the radius of the sphere.
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GUIDED PRACTICE
3. A spherical balloon has an initial radius of
5 in. When more air is added, the radius becomes
10 in. Explain how the S.A. changes as the
radius changes.
10 in
5 in
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Volume of a Sphere

• The volume V of a sphere is
• Where r is the radius of the sphere

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EXAMPLE 4
A soccer ball has a diameter of 9 inches. Find
its volume.
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Find the volume of the sphere
EXAMPLE 5
10 cm
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GUIDED PRACTICE
4. The radius of a sphere is 5 yards. Find the
volume of the sphere. Round your answer to two
decimal places.
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5. A spherical balloon has an initial radius of
5 in. When more air is added, the radius becomes
10 in. Explain how the volume changes as the
radius changes.
GUIDED PRACTICE
10 in
5 in
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GUIDED PRACTICE
6. The volume of a sphere is 614 m3.
What is the diameter of the sphere?