Page 356 - Math Smart - 7

Example 1

6 cm
Calculate the surface area of this cuboid.
3 cm

Solution
You can draw the net of the cuboid to help you. Use the
information given to label the sides of the net.
6 cm
6 cm
B
3 cm
6 cm 3 cm 3 cm

A C A C
Cuboid
B

6 cm
Net of the cuboid
Find the area of each face.
Area of face A: 6 x 3 = 18 cm^
Area of face B: 6 x 3 = 18 cm^
Area of face C: 3 x 3 = 9 cm^
Surface area of the cuboid = (Area of face A x 2) + (Area of face B x 2) +
(Area of face C x 2)
= (18 X 2)+ (18 x 2) + (9 X 2)
= 36 + 36 + 18
= 90 cm^
Try and Apply!

Draw the nets of the
4 cm
cuboids shown on a piece
of square grid paper to
find out if they have the
same surface area. (Each
square grid is 1 cm^.)

Hint: The net of cuboid A
has been drawn for you.
Draw the net of cuboid B.
2 cm

Check that the dimensions of your net of cuboid B is correct by cutting out the net you have drawn
and folding it into a solid. Measure the length, width and height of the cuboid you have made. Is it the
same as the dimensions given in the diagram?

UNIT 15 Measuring Time, Area, Perimeter and Volume