1. Surface Area
Rectangular Prisms
Notes Page 46

2. The surface area of a three- dimensional figure is the sum of the areas of its surfaces. To help you see all the surfaces of a three-dimensional figure, you can use a net. A net is the pattern made when the surface of a three-dimensional figure is layed out flat showing each face of the figure.

3. Additional Example 1A: Finding the Surface Area of a Prism
Find the surface area S of the prism.
Method 1: Use a net.
Draw a net to help you see each face of the prism.
Use the formula A = lw to find the area of each face.

4. Additional Example 1A Continued
A: A = 5  2 = 10
B: A = 12  5 = 60
C: A = 12  2 = 24
D: A = 12  5 = 60
E: A = 12  2 = 24
F: A = 5  2 = 10
Add the areas of each face.
S = = 188
The surface area is 188 in2.

5. Additional Example 1B: Finding the Surface Area of a Prism
Find the surface area S of each prism.
Method 2: Use a three-dimensional drawing.
Find the area of the front, top, and side, and multiply each by 2 to include the opposite faces.

6. Additional Example 1B Continued
Front: 9  7 = 63
63  2 = 126
Top: 9  5 = 45
45  2 = 90
Side: 7  5 = 35
35  2 = 70
S = = 286
Add the areas of each face.
The surface area is 286 cm2.

7. Check It Out: Example 1A
Find the surface area S of the prism.
Method 1: Use a net. A
3 in.
3 in.
6 in.
6 in.
3 in.
3 in.
6 in.
11 in.
11 in. B C D E F
3 in.
Draw a net to help you see each face of the prism.
Use the formula A = lw to find the area of each face.

8. Check It Out: Example 1A
A: A = 6  3 = 18 A
3 in.
B: A = 11  6 = 66
3 in.
6 in.
6 in.
3 in.
C: A = 11  3 = 33
11 in.
D: A = 11  6 = 66 B C D E
E: A = 11  3 = 33 F
3 in.
F: A = 6  3 = 18
Add the areas of each face.
S = = 234
The surface area is 234 in2.

9. Check It Out: Example 1B
Find the surface area S of each prism.
Method 2: Use a three-dimensional drawing.
top
side
front
8 cm
10 cm
6 cm
Find the area of the front, top, and side, and multiply each by 2 to include the opposite faces.

10. Check It Out: Example 1B Continued
top
side
front
8 cm
10 cm
6 cm
Front:  6 = 48
48  2 = 96
Top:  6 = 60
60  2 = 120
Side:  8 = 80
80  2 = 160
S = = 376
Add the areas of each face.
The surface area is 376 cm2.