Find the area of the shaded region in Fig. 12.20, if radii of the two concentric circles with centre O are 7 cm and 14 cm respectively and $$\angle AOC = 40°$$

Asked by Pragya Singh | 1 year ago |  101

#### 1 Answer

##### Solution :-

Angle made by sector = 40°,

Radius the inner circle = r = 7 cm, and

Radius of the outer circle = R = 14 cm

We know,

Area of the sector = ($$\dfrac{ θ}{360°}$$)×πr2

So, Area of OAC = ($$\dfrac{ 40°}{360°}$$)×πrcm2

= 68.44 cm2

Area of the sector OBD = ($$\dfrac{ 40°}{360°}$$)×πrcm2

= ($$\dfrac{1}{9}$$)×($$\dfrac{22}{7}$$)×7= 17.11 cm2

Now, area of the shaded region ABDC = Area of OAC – Area of the OBD

= 68.44 cm2 – 17.11 cm= 51.33 cm2

Answered by Abhisek | 1 year ago

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