In the adjoining figure the area enclosed between the concentric circles is 770 cm square. lf the radius of the outer circle is 21 cm , calculate the radius of inner circle.
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Answer:
Area of outer circle=πr^2
=22/7 multiply 21x21
=66x21=1386cm square
area enclosed between circles =770 cm square
so area of inner circle =1386-770=616 cm square
area of inner circle =πr^2=22/7 multiply r^2
616x7/22=r^2
4312/22=r^2
392/2=r^2
196=r^2
r=14 cm
Step-by-step explanation:
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Answered by
1
Step-by-step explanation:
Area of outer circle=πr^2
=22/7 multiply 21x21
=66x21=1386cm square
area enclosed between circles =770 cm square
so area of inner circle =1386-770=616 cm square
area of inner circle =πr^2=22/7 multiply r^2
616x7/22=r^2
4312/22=r^2
392/2=r^2
196=r^2
r=14 cm
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