RS Aggarwal Class 7 Mathematics Twentieth Chapter Mensuration Exercise 20F Solution
EXERCISE 20F
(1) Find the area of a circle whose radius is (i) 21 cm, (ii) 3.5 m.
(2) Find the area of a circle whose diameter is (i) 28 cm, (ii) 1.4 m.
(3) The circumference of a circle is 264 cm. Find its area.
(4) The circumference of a circle is 35.2 m. Find its area.
(5) The area of a circle is 616 cm2. Find its circumference.
(6) The area of a circle is 1386 m2. Find its circumference.
(7) The ratio of the radii of two circles is 4 : 5. Find the ratio of their areas.
(8) A horse is tied to a pole in a park with a string 21 m long. Find the area over which the horse can gaze.
(9) A steel wire when bent in the form of a square encloses an area of 121 cm2. The same wire is bent in the form of a circle. Find the area of the circle.
(10) A wire is in a circular shape of radius 28 cm. If it is bent in the form of a square, what will be the area of the square formed?
(11) A rectangular sheet of acrylic is 34 cm by 24 cm. From it, 64 circular buttons, each of diameter 3.5 cm, have been cut out. Find the area of the remaining sheet.
(12) A rectangular ground is 90 m long and 32 m broad. In the middle of the ground there is a circular tank of radius 14 metres. Find the cost of turfing the remaining portion at the rate of Rs 50 per square metre.
(13) In the given figure, four equal circles are described about the four corners of a square so that each circle touches two of the circles as shown in the figure. Find the area of the shaded region, each side of the square measuring 14 cm.
(14) A horse is tethered to one corner of a rectangular field, 60 m by 40 m, by a rope 14 m long. On how much area can the horse graze?
(15) In the given figure. A circle of diameter 21 cm is given. Inside this circle, Two circles with diameters 2/3 and 1/3 of the diameter of the big circle have been drawn, as shown in the given figure. Find the area of the shaded region.
(16) In the given figure a rectangular plot of land measures 8 m by 6m. In each of the corners, there is flower bed in the form of a quadrant of a circle of radius 2m. Also, there is flower bed in the form of a circle of radius 2 m in the middle of the plot. Find the area of the remaining plot.
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