Area A = pi(36-4)
= pi (81 -r^2)
so
32 = 81 - r^2
seven
An annulus is a ring bounded by two concentric circles. In annulus A
has an inner circle of radius 2 cm and an outer circle of radius 6 cm. Annulus B has an outer circle of radius 9 cm. If annulus B has an area equal to that of
annulus A, what is the radius of the inner circle of annulus B?
1 answer
1 answer