Surface Area of Prisms and Cylinders

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Surface Area of Prisms and Cylinders

• Lesson 9-8

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Vocabulary

• A net is a pattern you can fold to form a
  three-dimensional figure.

This is a net for a triangular prism.
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• The surface area of a three-dimensional figure is
  the sum of the areas of its surfaces.
• Find the area of each surface, and add all the
  areas together.

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Example 1
Triangles
A ½ bh
A ½ (26)(18)
8 cm
A ½ (468)
18 cm
A 234 cm2
26 cm
2 Tris 234 x 2 468 cm2
Left Rectangle
Front and Back Rectangles
A lw
A lw
A (26)(8)
A (18)(8)
A 208 cm2
A 144 cm2
2 Rects 208 x 2 416 cm2
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Add up the areas to find surface area.
S.A. 468 cm2 144 cm2 416 cm2
S.A. 1,028 cm2
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Surface Area of a Cube

• A cube has 6 congruent square faces.
• Find the area of one face, and multiply it by 6.

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Example
A s2
A 72
A 49 in2
7 in
S.A. 49(6)
S.A. 294 in2
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Surface Area of a Cylinder

• A cylinder consists of two circle bases and one
  rectangular side.
• The length of the rectangle is equal to the
  circumference of the circle.
• Find the area of the circles and add it to the
  area of the rectangle.

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Example
Rectangle
5 m
The width of the rectangle is the height of the
cylinder (16 m). The length of the rectangle is
the circumference of the circle.
16 m
Area of the circles
C 2?r
C 2(3.14)(5)
A ?r2
C 31.4 m
A 3.14(52)
A lw
A 3.14 (25)
A 31.4(16)
A 78.5 m2
A 502.4 m2
2 circles 78.5 x 2 157 m2
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Put the areas together
S.A. 157 m2 502.4 m2
S.A. 659.4 m2
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Homework Time