1. Surface Area of Prisms and Cylinders
Lesson 9-8

2. Vocabulary
A net is a pattern you can fold to form a three-dimensional figure.
This is a net for a triangular prism.

3. 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.

4. Example 1 A = ½ bh A = ½ (26)(18) A = ½ (468) A = 234 cm2 A = lw
Triangles
A = ½ bh
A = ½ (26)(18)
8 cm
A = ½ (468)
18 cm
A = 234 cm2
26 cm
2 Tri’s: 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 Rect’s: 208 x 2 = 416 cm2

5. Add up the areas to find surface area.
S.A. = 468 cm cm cm2
S.A. = 1,028 cm2

6. Surface Area of a Cube A cube has 6 congruent square faces.
Find the area of one face, and multiply it by 6.

7. Example
A = s2
A = 72
A = 49 in2
7 in
S.A. = 49(6)
S.A. = 294 in2

8. 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.

9. Example Rectangle 5 m 16 m Area of the circles C = 2r C = 2(3.14)(5)
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 = 3.14 (25)
A = lw
A = 31.4(16)
A = 78.5 m2
A = m2
2 circles: 78.5 x 2 = 157 m2

10. Put the areas together:
S.A. = 157 m m2
S.A. = m2

11. Homework Time