ML Aggarwal CBSE Solutions Class 7 Math Thirteenth Chapter Perimeter and Area Exercise 13.3

(1) Find the circumference of the circles with the following radius:

(i) 7 cm  (ii) 21 cm  (iii) 28 mm (iv) 3.5 cm.

(2) Find the area of the circes, given that:

(i) radius = 14 mm (ii) diameter = 49 m (iii) diameter = 9.8 cm (iv) radius = 5 cm

Solution:

(3) find the circumference and area of a circle of radius 20 cm. (use π = 3.14)

(4) The minute hand of a tower clock is 1.4 m long. How far does the tip of the hand move in 1 hour?

Solution:

(5) A gardener wants to fence a circular garden of diameter 21 m. Find the length of the rope he needs to purchase, if he makes 2 rounds of fence. Also find the cost of the rope, if it costs Rs. 4 per metre.

(6) If the circumfarence of a circle exceeds its diameter by 30 cm, find the radius of the circle.

Solution:

(7) Find the length of the diameter of a circle whose circumfarence is 44 cm.

(8) The circumfarence of a circle is 31.4 cm. Find the radus and the area of the circle.

(9) Find the radius and the circumference of a circle whose area is 144π cm square.

Solution:

(10) How many times will the wheel of a car rotate in a journey of 88 km, given that the diameter of the wheel is 56 cm?

(11) From a square cardboard of side 21 cm, a circle of maximum area is cut out. Find the area of the cardboard left.

Solution:

(12) A piece of wire is bent in the shape of an equilateral triangle of side 4.4 cm. If this wire is rebent to form a circle, find the radius and the area of the circle.

(13) A wire in the form of a square of side 27.5 cm. It is straightened and bent into the shape of a circle. Find the area of the circle.

Solution:

(14) A wire is in the form of a rectangle 18.7 cm long and 14.3 cm wide. If this wire is reshaped and bent in the form of circle, find the radius and the area of the circle so formed.

(15) The diameter of a circular park is 84 m. On its outside, there a 3.5 m wide road. Find the cost of constructing the road at Rs. 240 per meter square.

Solution:

(16) A circular pond is surrounded by a 2 m wide circular path. If the outer circumference of the circular path is 44 m, find the inner circumference of the circular path. Also find the area of the path.

Solution:

Πr2 – Πr2

= 22/7 x 7 x 7 – 22/7 x 5 x 5

= 154 – 78.57

= 75.43 m2

(17) In the adjoining figure, the area enclosed between the concentric circles is 770 cm square. If the radius of the outer circle is 21 cm, calculate the radius of the inner circle.

(18) From a circular card sheet of radius 14 cm, two circles of radius 3.5 cm and a rectangle of length 3 cm and breadth 1 cm are removed.

Solution:

____ x ____


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