Page 104 - Maths Skill - 6

102 Maths

Example 5: Find the perimeter of a regular pentagon with each side measuring 6 m.
Solution: Perimeter of a regular pentagon = 5 × Side = 5 × 6 m = 30 m.

Example 6: Find the side of an equilateral triangle whose perimeter is 45 m.
Solution: Perimeter of an equilateral triangle = 3 × Side
Perimeter of an equilateral triangle
\ Side of an equilateral triangle = 3

45
= m = 15 m
3
Example 7: The perimeter of a regular hexagon is 78 cm. How long is its side?
Solution: Perimeter of a regular hexagon = 6 × Side
Perimeter of a regular hexagon
\ Each side = 6

78
= cm = 13 cm
6
Example 8: The length and breadth of a rectangular field are 15.7 m and 11.2 m respectively. Find the cost of
fencing its four sides at the rate of ` 12.50 per metre.
Solution: Perimeter of the field = 2 × (length + breadth)
= 2 × (15.7 + 11.2) m = 2 × 26.9 m = 53.8 m
 Cost of fencing 1 metre = ` 12.50
\ Cost of fencing 53.8 metres = ` (12.50 × 53.8) = ` 672.50

Exercise 7.1

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

(i) (ii) (iii) (iv)

2. Find the perimeter of each of the following figures.
4 cm 4 cm 2 m
5 cm 1 m 3 m
8 cm 6 cm 4 cm 4 cm 4 cm 4 cm 4 cm 4 cm 2 m 3 m
1 m
2 m
6 cm 2 cm 2 cm 2 m 1 m 4 m
6 cm 7 cm 2 cm 2 cm 4 cm 4 cm 4 cm 4 cm 1 m 4 m 4 m
9 cm 1 cm 1 cm 4 cm 4 cm 8 m 4 m
(i) (ii) (iii) (iv) (v)

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

0.5 m
10 m 25 m
5 m 5 m 12 m 20 cm
10 m 15 m 25 m
(i) (ii) (iii) (iv)