Question

7. In the adjoining figure, the area enclosed between the
concentric circles is 770 cm? If the radius of the outer circle
is 21 cm, calculate the radius of the inner circle.​

Answer 1

Answer:

1. 22/7(R²-r²) is equal to 770
2. 21²-r² is equal to 770×7/22=245
3. 441-r²=245
4. r²=245-441=196
5. r=√196=14
6. final answers is 14