c You can find the surface area (S.A.) of any prism by adding the areas
of all the faces.
EXAMPLE
To find the surface area of the trapezoidal prism shown, you need to
1
2
use the formula A = }} (b1 + b2)h for the area A of a trapezoid with
height h and base lengths b1 and b2.
2m
5m
4m
5m
5m
5m
4m
8m
2m
8m
3m
3m
2m
S.A. = areas of trapezoids + areas of rectangles
3 12
4
= 2 }} (8 + 2)4 + 5 p 3 + 8 p 3 + 5 p 3 + 2 p 3
= 40 + 15 + 24 + 15 + 6
= 100
The surface area of the trapezoidal prism is 100 m2.
✔
QUESTION 5
…checks that you
can find the surface
area of a prism.
420
Module 6
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
4
Sketch a net for each prism. Label the length of each edge.
a.
b.
5 cm
6 cm
6 ft
5 cm
4 cm
12 ft
5 ✔
CHECKPOINT
4 ft
4 cm
Find the surface area of each prism in Question 4.
c Surface Area of a Pyramid You can use a method similar to the one
in the Example to find the surface area of a pyramid.
6
a. Use Labsheet 3A. Cut out the Square Pyramid Net and fold it
to make a pyramid with a square base.
b. Use a ruler to help you find the surface area of the pyramid.
c. Measure the height of the pyramid.
d. Did you need the height of the pyramid to find its surface area?
What information did you need?
Architects and Engineers