1. Area vs Surface Area

2. Surface Area
Surface Area is the sum of the area of all of the faces of a 3-dinemtional figure.
We often use nets to help us determine surface area.
2-D (flat) figures have area
3-D figures have surface area

3. Surface Area vs. Area
State whether each of the following shapes will have area or surface area.

4. Surface Area vs. Area
State whether each of the following situations will involve area or surface area.
I want to wrap the new PS3 that I bought as a gift. (Hint: it is in the box still)
I just bought property and I want to measure how much land I own.
I am painting a shed and I need to know how much paint to buy.
I am painting one wall of my house and I need to know how much paint to buy.
Surface Area
Area
Surface Area
Area

5. Finding Surface Area We can calculate surface area in two ways:
Substitute into a formula.
Draw a net and find the area of each section.
*If you do not know the formula, the second option will always work!

6. Surface Area Using a Net
Use your knowledge of area to calculate the surface area of the rectangular prism.
Draw a net first to help you.
4cm
3 cm
7 cm

7. Surface Area Length = 7 cm Width = 3 cm Height = 4 cm Add!
SA = 122 cm2
3 cm
Top= 21 cm2
7 cm
Back = 28 cm2
4 cm
7 cm
3 cm
3 cm
Bottom= 21 cm2
Base
= 12 cm2
3 cm
Base
= 12 cm2
4 cm
4 cm
4 cm
Front= 28 cm2
7 cm

8. Surface Area All four triangles are the same: A = ½ bh
A = ½ (3)(4) = 6 cm2
Area of the base (square)
A = LW or A=s2
A = 32 = 9 cm2
Total Surface Area =
4 triangles + 1 square
= 4(6 cm2 ) + 9 cm2 = 33 cm2
4 cm
3 cm

9. Surface Area using a Formula
Surface area of a Rectangular Prism
SA = 2LW + 2LH + 2HW
SA = 2(7)(3) + 2(7)(4) + 2(3)(4)
SA = 122 cm2
Length = 7 cm
Width = 3 cm
Height = 4 cm

10. Common Surface Area Formulas
Rectangular Prism
SA = 2LW + 2LH + 2WH
Square Pyramid
SA = 2bh + b2
Cube
SA = 6s2

11. Activity
Using the object you brought in and a ruler, determine how much paper would be needed to wrap the outside of your object.
Hint: This means we need to find the surface area. You can do this using a formula or by drawing a net.