Page 110 - Revised Maths Wisdom Class - 6

108 MATHS

Perimeter of rectangle = 2(l + b) = 2(5x + 2x) = 4228
4228
⇒ 7x =
2
4228
⇒ x = = 302
27×
Therefore, length = 5 × 302 = 1510 cm = 15 m 10 cm

breadth = 2 × 302 = 604 cm = 6 m 4 cm

Example 4: The perimeter of a square painting is 5 m 40 cm. Find the length of each side.
Solution: Let the length of each side be x cm
Perimeter of square = 5 m 40 cm = 540 cm [1 m = 100 cm]
Perimeter of square = 4 × side
540
⇒ 540 = 4 × x ⇒ x = 4 = 135

Hence, length of each side of square painting is 135 cm.

Example 5: The cost of fencing a rectangular garden of breadth 250 m at the rate of ` 18.50 per metre is
` 27750. Find its length.
Solution: Total cost of fencing = ` 27750
Cost of fencing per metre = ` 18.50
27750
Perimeter of rectangular garden = = 1500 m
18 50.
Let the length of the garden be ‘x’ m.

Perimeter = 2 (l + b)
1500
⇒ 1500 = 2 (x + 250) ⇒ x + 250 = = 750
2
⇒ x = 750 – 250 = 500

Hence, the length of the rectangular garden is 500 m.

Example 6: The perimeter of a regular polygon is 444.5 cm and length of each side is 63.5 cm. Find the number
of sides of this polygon. What is it called?
Solution: Perimeter of polygon = 444.5 cm
Length of each side = 63.5 cm

Let ‘n’ be the number of sides
Perimeter = n × length of each side
Perimeter 444 5.
⇒ n = = = 7
length 63 5.

Hence, the number of sides is 7 and it is called heptagon.

Example 7: Samita has a metal string of length 120 cm long. She is trying to make a regular polygon with this
string. How many types of regular polygon she can make? Also, find the length of each side of
possible polygon.

Solution: 120 is divisible by 3, 4, 5, 6, 8, 10 and 12. So, the possible polygons will be equilateral triangle,
square, pentagon, hexagon, octagon, decagon and dodecagon.