Area and Perimeter
Area
- The area is defined as the space occupied by the flat surface of a particular shape.
- Let us learn how to find the area of rectangle and square.
Rectangle
- A rectangle has two dimensions namely length and breadth.
- The formula to calculate the area of the rectangle is Area = Length Ă— Breadth
- The unit of the area is square unit.
Example:
Find the area of the rectangle with a length of 20 cm and a breadth of 12 cm.
Solution:
Length of the rectangle = 20 cm
Breadth of the rectangle = 12 cm
Area of the rectangle = 20 cm Ă— 12 cm
= 240 square cm
Square
- All sides of the square are equal in length.
- The formula to calculate the area of the square is
Area = Side Ă— Side
Example:
Find the area of a square with a side of 9 cm.
Solution:
Side of the square = 9 cm
Area of the square = 9 cm Ă— 9 cm
= 81 square cm
Unit of Area
- Area is the product of length and breadth which is in linear units.
- When the area of the rectangle is calculated then it has to be made sure that the unit of the length and breadth are the same.
- When we multiply two same linear units, we get the square unit.
- Therefore, the area is always measured in a square unit.
- For example, the area of the rectangle with length and breadth of 15 m and 12 m is 180 square m.
Area of combining shapes
Example:
Four squares on each side 4 m are combined together to get a rectangle. Find the area of the resultant rectangle.
Solution:
Step 1:
The side of the square = 4 m
Area of the square = 4 m Ă— 4 m = 16 square m
Step 2:
Number of squares = 4
Area of each square = 16 square m
Area of 4 squares = (16 Ă— 4) = 64 square m
Alternate Way:
The length of the resultant rectangle = (4 + 4 + 4 + 4) m = 16 m
The breadth of the resultant rectangle = 4 m
Area of the resultant rectangle = 16 m Ă— 4 m
= 64 square m
Common Mistakes
Children often overlooked the units of length and breadth.
For example:
Calculate the area of the rectangle of the length of 12 m and breadth of 250 cm.
Wrong solution:
Length of rectangle = 12 m
Breadth of rectangle = 250 cm
Area = (12 Ă— 250) = 3,000 square m.
Correct solution:
Length of rectangle = 12 m
Breadth of rectangle = 250 cm
We know 1 m = 100 cm.
Therefore, 250 cm = (250 Ă·
100) = 2.5 m.
Area = 12 m Ă— 2.5 m = 30 square m.
Did you know?