Geometry

Surface Area of Rectangular Prisms

Surface Area

Surface Area – the total area of all the surfaces, or faces, of an object.

To find the surface area of an object we can add up the areas of the separate faces.

lw

h

Surface Area

Example: This is a rectangular prism. The l, w and h have different values.

lw

h

Do any of the sides have the same size and shape?

Surface Area

In a rectangular prism there are three pairs of opposite and equal sides.

lw

h

We can find the surface area of this prism by adding the areas of the two brown sides (A), the two green sides (B) and the two red sides (C).

C

BA

Surface Area

We should use a table to tabulate the various areas.

5cm3cm

4cm

Example: Side Area Number of Sides

Total Area

A

B

C

TOTAL

C

BA

Surface Area

We should use a table to tabulate the various areas.

5cm3cm

4cm

Example: Side Area Number of Sides

Total Area

A 20cm2 2 40cm2

B

C

TOTAL

C

BA

Surface Area

We should use a table to tabulate the various areas.

5cm3cm

4cm

Example: Side Area Number of Sides

Total Area

A 20cm2 2 40cm2

B 12cm2 2 24cm2

C

TOTAL

C

BA

Surface Area

We should use a table to tabulate the various areas.

5cm3cm

4cm

Example: Side Area Number of Sides

Total Area

A 20cm2 2 40cm2

B 12cm2 2 24cm2

C 15cm2 2 30cm2

TOTAL

C

BA

Surface Area

We should use a table to tabulate the various areas.

5cm3cm

4cm

Example: Side Area Number of Sides

Total Area

A 20cm2 2 40cm2

B 12cm2 2 24cm2

C 15cm2 2 30cm2

TOTAL

6 94cm2

C

BA

Surface Area

Now you try...find the surface area!

1.9cm

3.2cm

2.8cm

Example:

C

B

AB

C

Side Area No of Sides

Area

Total

Surface Area

Can we calculate a formula for the area of a rectangular prism?

Surface Area

Formula – Surface Area of a Rectangular Prism

SA = 2lw + 2wh + 2lh