1. Surface area
The surface area of a solid is found by adding the areas of all its faces.
To calculate the surface area you may first sketch the net of the shape.

2. Example 1 5m 9m Find the surface area of the following Base Front
Right
Left
Top
Back 5m 4m 5m 4m 9m
Left/right = 2 × 4 × 5
= 40 9m 4m
Base/top
Base/top = 2 × 9 × 4
= 72
Back/front = 2 × 5 × 9
= 90
Back/front
SA =
= 202m2

3. Example 2 Find the surface area of the following 7m 5m 12m 7m 12m 5m
Back
Base
Front
x m
x2 =
x2 = 169
x = 13
Front = 13 × 7
= 91
Back = 5 × 7
= 35
Sides = 2 × ½ × 12 × 5
= 60
Base = 12 × 7
= 84
SA =
= 270m2

4. Example 3 12m 5m Find the surface area of the following 5 m 12 m C m
What is the length of the rectangle?
The same as the
circumference
of the circle!
Rect = LB
= 2πr × h
= 2 × π × 5 × 12
= 377·0
Circles = 2 × πr2
= 2 × π × 52
= 157·1
OR SA = 2πrh + 2πr2
= 2×π×5×12+2×π×52
= 377·0
SA = 377· ·1
= 534·1 m2

5. Example 4 12 m 7 m 11 m 10 m Find the surface area of the following
Base = LB
= 7 × 12
= 84
Front/back = 2 × ½ × bh
= 2 × ½ × 7 × 11
= 77
Sides = 2 × ½ × bh
= 2 × ½ × 12 × 10
= 120
SA =
= 281 m2

6. Today’s work Exercise 6d page 203
Q1f, Q2e, 3a, 5a, 7bc, 8aeh, 9adef, 10ad, 12