Surface Area of Cylinders

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Surface Area of Cylinders
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SURFACE AREA of a CYLINDER.
Imagine that you can open up a cylinder like so
You can see that the surface is made up of two
circles and a rectangle.
The length of the rectangle is the same as the
circumference of the circle!
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EXAMPLE Round to the nearest TENTH.
Top or bottom circle A pr² A p(3.1)² A
p(9.61) A 30.2 cm²
Rectangle C length The length is the same as
the Circumference C p dC p(6.2)C 19.5
cm Now the area A lwA 19.5(12)A 234 cm²
Now add
30.2 30.2
234
SA 294.4 in²
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Example 1
Rectangle
C 2?r
5 m
C 2(3.14)(5)
C 31.4 m
A lw
16 m
A 31.4(16)
A 502.4 m2
Area of the circles
Put the areas together
A ?r2
A 3.14(52)
S.A. 157 m2 502.4 m2
A 3.14 (25)
S.A. 659.4 m2
A 78.5 m2
2 circles 78.5 x 2 157 m2
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EX2) S 2pr2 2prh
2p(42) 2p(4)(6)
80p in2 ? 251.2 in2
15 cm
EX3) S 2pr2 2prh
3 cm
2p(152) 2p(15)(3)
540p in2 ? 1695.6 cm2
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Example 4)
A cylindrical soup can is 7.6 cm in diameter and
11.2 cm tall. What is the area of the label that
covers the side of the can?
Only the lateral surface needs to be covered.
L 2?rh
2?(3.8)(11.2)
Diameter 7.6 cm, so r 3.8 cm.
267.3 cm2
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notes
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Surface Area of Cylinders

• Date______________

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SURFACE AREA of a CYLINDER.
Imagine that you can open up a cylinder like so
You can see that the surface is made up of two
circles and a rectangle.
The length of the rectangle is the same as the
circumference of the circle!
10
Example 1
Rectangle
5 m
16 m
Area of the circles
Put the areas together
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EX2) S 2pr2 2prh
EX3) S 2pr2 2prh
12
Example 4)
A cylindrical soup can is 7.6 cm in diameter and
11.2 cm tall. What is the area of the label that
covers the side of the can?