Page 169 - Ganit Kaushal

Ex 8. What would be the cost of fencing a rectangular park whose length is 150 m and breadth is 120 m, if
the fence costs `40 per metre? (NCERT)
Sol. Perimeter of the rectangular park = 2 × (150 m + 120 m) 150 m

= 2 × (270 m) = 540 m
Now, the cost of one metre of fencing = `40 120 m
\ The cost of 540 metres of fencing = `(40 × 540) = `21600

Exercise 6.1

1. Rashi wants to put lace all around a rectangular tablecloth that is 3 m long and 2 m wide. Find the
length of the lace required. (NCERT)
2. Find the distance travelled by Usha if she takes three rounds of a square park of side 75 m. (NCERT)

3. Find the length of the third side of a triangle having a perimeter of 55 cm and having two sides of
length 20 cm and 14 cm, respectively. (NCERT)

4. A piece of string is 36 cm long. What will be the length of each side, if it is used to form:
(a) A square,
(b) A triangle with all sides of equal length, and

(c) A hexagon (a six-sided closed figure) with sides of equal length? (NCERT)
5. A rectangular paper chit of dimensions 6 cm × 4 cm is cut, as shown in the adjoining 4 cm
figure, into two equal pieces. These two pieces are arranged in different ways.

Now, based on it, find out the length of the boundary (i.e., the perimeter) of each of 6 cm
the following arrangements. (NCERT)

6 cm 6 cm 3 cm
2 cm 2 cm 2 cm

2 cm
(a) (b) (c) (d)
6. The cost of fencing a square garden is `400, at the rate of `1 per metre. Find the side of the square.

7. If the perimeter of a rectangular field is 200 m and its breadth is 40 m, find its length.
8. The perimeter of a triangle is 540 m and its sides are in the ratio 25:17:12. Find the measurement of
each of its sides. [Hint: Take sides 25a, 17a, 12a for some constant a]
9. The length and breadth of a rectangular field are in the ratio of 3:2. If the perimeter of the field is
80 m, find its breadth (in metres).

10. Gopi runs around a rectangular park with a length of 50 m and a breadth of 35 m. Mohan runs around
a square park with a side of 65 m. Who covers more distance?

Perimeter and Area 167