Q5 of 36 Page 253

and are two mutually perpendicular radii of a circle of radius 10.5 cm. D and OD = 6 cm. Find the area of blue coloured region shown in figure 13.23.


Figure 13.23


given OA = 10.5 cm = radius (r)


OD = 6 CM


we can see that ODA is a right-angled triangle


area of triangle = OA× OD


= 10.5 × 6


= 31.5 cm2


we can see that segment OACB is of the circle.


so, the area of OACB = × r2


= × 10.52


= 86.54625 cm2


area of blue colored region = area of OACB - area of triangle


= 86.54625 – 31.5


= 55.04625 cm2


More from this chapter

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3

What will be the cost of covering the white portion in figure 13.21 with a silver foil if the rate is Rs. 100 per m2? (π = 3.14)


Figure 13.21


 4

ABCD is a square plate of 1 m length. As shown in figure circles are drawn with their center at A, B, C, D respectively, each with radius equal to 42 cm. The blue coloured part at each corner, as shown in the C figure 13.22 is cut. What is the area of the remaining portion of the plate?


Figure 13.22


 1

The area of a circular park is 616 m2. There is a 3.5 m wide track around the park running parallel to the boundary. Calculate the cost of fencing on the outer circle at the rate of Rs. 5 per meter.

 2

A man is cycling in such a way that the wheels of the cycle are making 140 revolutions per minute. If the diameter of the wheel is 60 cm, then how much distance will he cover in 2 hours?