SURFACE AREAS
AND VOLUMES
Q. The side of a cube is 60 cm. Find the total surface area of the cube.
∴ Total surface area of the cube is 21600 cm2.
Total surface area of the cube =
Sol.
6l2
= 6 ×
(60)2
= 6 ×
3600
= 21600 cm2
What is formula for finding Total surface area of cube?
6l2
length (l ) = 60 cm
6l2
∴ Total surface area of the cube is 216 cm2
and Volume of the cube is 216 cm3
Perimeter of one face of cube
Sol.
Perimeter of square
= 4l
24
l =
24
4
∴ l = 6 cm
Total surface area of cube =
= 6 ×
(6)2
= 6 ×
36
= 216 cm2
Volume of cube =
l3
= (6)3
= 216 cm3
l
What is formula for finding Total surface area of cube?
6l2
What is formula for finding Volume of cube?
l3
What is formula for finding Perimeter of square ?
4l
=
∴
∴
Q. Perimeter of one face of cube is 24 cm.
Find (i) the total area of the 6 faces (ii) the volume of the cube.
6l2
Q. The volume of a cube is 1000 cm3. Find its total surface area.
∴ Total surface area of the cube is 600 cm2.
Volume of a cube =
Sol.
l3
= l3
∴ 1000
10 cm
∴ l =
[Taking cube roots]
Total surface area of a cube =
= 6 ×
(10)2
= 6 ×
100
= 600 cm2
What is formula for finding Volume of cube?
l3
What is formula for finding Total surface area of cube?
6l2