Page 7 - Lesson Notes-Ch.13 SA and Volumes(Cuboids and Cubes)

2
Volume of the cube = ×

Volume of the cube = cubic unit
Perimeter of Cube and Cuboid

The perimeter of cuboid will be based on its length, breadth and height.
Since the cuboid has 12 edges and the value of its edges are different from
each other, therefore, its perimeter is given by:

Perimeter of a cuboid = 4 (l + b + h)

where, l is the length, b is the breadth, h is the height.

The perimeter of the cube also depends upon a number of edges it has and
the length of the edges. Since the cube has 12 edges and all the edges
have equal length, therefore the perimeter of the cube is given by:

Perimeter of a cube =
where is the length of the edge of the cube.

Example-1

What is the surface area of a cereal box whose length, breadth and height
is 20 cm, 8 cm and 30 cm respectively?

Solution

Given, Length = 20 cm Breadth = 8 cm Height = 30 cm

Total surface area of the cereal box = 2(lb + bh + lh)

= 2(20 × 8 + 8 × 30 + 20 × 30)

7