14.2.1 Cuboid
The shapes like a closed match box are examples of a cuboid. Touch your hand on the top of the match box. This plane surface is the face of match box. How many faces does a match box have?
Now take an eraser, whose shape is similar to that of a match box. Touch your hand along its faces, edges and vertices.
Does the eraser have the same number of faces, edges and vertices as that of match box? You will find this to be true.
Objects like match boxes, erasers etc. are in the shape of a cuboid and have 6 faces,
12 edges and 8 vertices. 14.2.2
A dice is an example of a cube. Take a dice. Locate its faces, edges andvertices. Count them. How many faces, edges and vertices does a dice have?
You will find that a die has 6 faces, 12 edges and 8 vertices, same as that of a cuboid Then what is the difference between a cube and a cuboid? You will find that the length, breadth and height of a cube are all same, but in a cuboid they are different. Verify this by measuring the length, breadth and height of an eraser and a die.
1. (i) What is the shape of the face of a cube?
(ii) What is the shape of the face of a cuboid?
2. Ramesh has collected some boxes in his room. Pictures of
these are given here. How many are cubes and how many
are cuboids.
3. Ajith has made a cuboid by arranging cubes of 2 centimeter each. What is the length, breadth and height of the cuboid so
formed?
14.2.3 Cylinder
Objects like a wooden log, a piece of pipe, A230 candle, tube light are in the shape of a cylinder. Take a candle. Slice it on the top as shown in the fig.1. Lay it down horizontally (fig 2). Can you roll it?
Now erect candle up vertically (fig.3). Does it roll?
Now take an eraser, whose shape is similar to that of a match box. Touch your hand along its faces, edges and vertices.
