Question

if the areas of two concentric are 154cm2 and 616cm2 respectively,then find the width and area of the circular path between them.​

Answer 1

Let r = radius of inner circle

area of inner circle = 154 cm2

⇒π r2 = 154⇒r2 = 154 × 7 22 = 49⇒r = 7 cm

Let R = radius of outer circle

area of outer circle = 616 cm2

⇒π R2 = 616⇒R2 = 616 × 722 = 196⇒R = 14 cm

width of ring = R - r = 14 - 7 = 7 cm