Page 132 - ICSE Math 4

Area is measured in square units, i.e., the unit of area is square cm or square m or any
other square unit. 1 cm 1 cm
A B
Consider a fi gure ABCD made up of 4 equal 1 cm I II 1 cm
squares as shown. The area of each square

in this fi gure is 1 square unit. 1 cm IV III 1 cm
D C
1 cm 1 cm
Area of fi gure ABCD = Area of (Square I + square II + square III + square IV)

= 1 square unit + 1 square unit + 1 square unit + 1 square unit
= 4 square units

Now let’s consider another example and fi nd the area of your school desk using books.

We can do so by keeping a book on the
table and tracing its outline using a chalk.
Cover the en re desk with books (of equal
length and size) and trace their outlines.

Now count the number of boxes that you
have drawn on the desk to fi nd the area of
desk.
Remember
We can see that the desk holds some
number of books, let’s say, 12 books to • 1 square centimetre can also be written
cover it completely where each book has as 1 sq. cm.
• 1 square metre can be written as
an area of 1 square unit. Hence, we can
1 sq. m.
say that the area of the desk is 12 square • 1 square kilometre can be written as
units. 1 sq. km.

Finding Area by Counting Squares

To fi nd the area of any plane object, we keep the object on a square grid and trace its
outline on it, in which the side of each square is of 1 cm. Then we fi nd the area of the
object by coun ng the number of squares covered by it.

Example 2: Find the area covered by an eraser on the given square
grid. The area of each square in the grid is 1 sq. cm.
ERASER
Solu on: From the given fi gure, we can say that the eraser covers
an area of 8 complete squares.

If the area of each square in the grid is 1 sq. cm, then we can say that the
eraser has an area of 8 sq. cm as 8 × 1 sq. cm = 8 sq. cm.
So, the area of the eraser is 8 square cen metres or 8 sq. cm.

Now let’s fi nd the area of some plane fi gures using a squared sheet of paper where the
area of each square is 1 square unit.

122