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 ∠ AOC = 40°.
Area of the shaded region = Area of Bigger sector –area of Smaller Sector
If R and r are the two radii of Bigger and Smaller circles respectively, then:
Area of shaded region = 
2
2 )
= 
2
2 )
= 51.33 sq cm
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