Page 357 - Math Smart - 7

Find the total surface area of this cuboid.

Hint Note the number of faces the cuboid has.
10 cm
3 cm
Solution
4 cm

3 cm

10 cm
10 cm 10 cm
3 cm 3 cm I
4 cm 4 cm 4 cm

Area of one blue Area of one red Area of one green Total surface area
rectangle face rectangle face rectangle face = 24 + 60 + 80
= 3x4 = 3 X 10 = 4 X 10 = 164 cm^
= 12 cm^ = 30 cm^ = 40 cm^
Area of two blue faces Area of two red faces Area of two green faces
= 12 X 2 = 30 X 2 = 40 X 2
= 24 cm^ = 60 cm^ = 80 cm^

Check My
Understanding

O The following are the nets of some solids. Calculate the surface area of each
solid based on the dimensions given,
a) ■) b) 6 cm 30 mm

30 mm
3 cm

10 cm 2 cm

3 cm

3 cm

O Calculate the surface area of these solids. Start by drawing the net of each solid
a) ^ ^ b) ^ c)

6 cm

cm
4 cm
2cm |i- •'
8 cm
5 cm 40 mm