Question

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.​

Answer 1

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:

please mark it brainliest answer and please don't forget to give me a thanks for this answer

Answer 2

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