Question

in the adjoining figure, the area enclosed between the concentric circles is 770 cm sq .if the radius of outer circle is 21 cm ,calculate the radius of the inner circle.

Answer 1

firstly find the area of outer circle by the formula of area of circle




then area of outer circle minus area bw concentric circle that is 770




then u will get area of inner circle


now find the radius from area i




if u know then ok if not then ask me in comment