Page 153 - Math Skill - 4

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Perimeter of a Square P Side S
A square is a quadrilateral with all its sides equal. Let us

consider a square PQRS and find its perimeter. Side Side
Perimeter of a square PQRS = PQ + QR + RS + SP [PQ = QR = RS = SP]
= 4 × side Q Side R

Hence, Perimeter of a square = 4 × side

Let’s Attempt

Example 1: Find the perimeter of a rectangle whose length is Fact-o-meter
18 metres and breadth is 5 metres. Always add the terms in
Solution: Perimeter of a rectangle = 2 × (l + b) brackets first and then
= 2 × (18 + 5) m multiply to calculate the
= 2 × 23 m = 46 m perimeter of rectangle.
Thus, the perimeter of the rectangle is 46 m.
Example 2: Find the perimeter of a square park of each side 90 m.
Solution: Perimeter of a square = 4 × side
= 4 × 90 m = 360 m
Thus, perimeter of the square park is 360 m.
Example 3: The length and breadth of a rectangular field are 57 m and 33 m respectively.
What length of wire will be required for fencing all around the field?

Solution: Length of wire for fencing = Perimeter of the field
Perimeter = 2 × (l + b) = 2 × (57 + 33) m = 2 × 90 m = 180 m
Thus, 180 m of wire will be required for fencing.

Exercise 11.1

1. Find the perimeter of each of the following figures.

(a) 5 cm (b) 5 cm (c) 5 cm

3 cm 3 cm 7 cm 1 cm

4 cm 2 cm 6 cm
6 cm 2 cm 3 cm 5 cm
1 cm

(d) 3 cm (e) 4 cm (f) 4 cm
6 cm 4 cm 7 cm 5 cm 5 cm
12 cm 10 cm 2 cm 6 cm

4 cm 4 cm 5 cm 3 cm 3 cm
5 cm 14 cm 12 cm