Class 9 | Chapter 13 | Surface areas and Volumes | Example 1

Example 1: Mary wants to decorate her Christmas tree. She wants to place the tree on a wooden box covered with coloured paper with picture of Santa Claus on it (see Fig. 13.4). She must know the exact quantity of paper to buy for this purpose. If the box has length, breadth and height as 80 cm, 40 cm and 20 cm respectively how many square sheets of paper of side 40 cm would she require?

Prerequisite

Finding surface area of a cube or a cuboid is quite simple. Every cube/cuboid has 6 sides. All we need is find the area of all six sides and add – this will be the total surface area of the cube/cuboid.

A cube is a cuboid that has all edges of equal length. Hence, every cube is a cuboid as well but every cuboid is not a cube. 

It is recommended to understand the core concept of area, surface area and volume before we attempt any question based on these concepts.

 
Derivation of formula – Surface area of cube and cuboid
 

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