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Circumference, Area,
Surface Area, and Volume
By Taylor Winter
Derive the Formula:
Surface area of a Sphere
Example Problems
1. A sphere has a radius of 4 cm. What is the surface area?
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Area of a sphere= 4πr^2
r= 4 cm
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(4 x π x 4 cm)^2= (16πcm)^2= 256πcm^2
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The surface area of the sphere is 256πcm^2.
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To find the surface area of a sphere you should imagine it cut in half like an orange.
The circle you see is called the great circle.
The area of 4 great circles make up the surface area of a sphere.
So the formula for a sphere is 4πr^2.
2. A globe in a classroom has a diameter of 12 inches. What is the surface area of the globe?
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Area of a sphere= 4πr^2
r= d/2= 12 in/2= 6in
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(4 x π x 6 in)^2= (24πin)^2= 576πin^2
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The surface area of the globe is 576πin^2.
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