Q22 of 45 Page 12

AB and CD are respectively arcs of two concentric circles of radii 21 cm and 7 cm and centre O (see Fig. 12.32). If ∠ AOB = 30°, find the area of the shaded region

(CBSE 2013)

Area of the shaded region = Area of sector OAEB - Area of sector OCFD

= * * (21)2 - * * (7)2


= * [(21)2 – (7)2]


= * [(21 – 7) (21 + 7)]


=


= cm2

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