Question

find the area of a flat circular ring formed by two concentric circles (circles with same centre) whose radii are 9cm and 5cm

Answer 1

the answer is 176. i hope it helps.

Answer 2

$area \: of \: ring \: = \pi { r_{1} }^{2} - \pi { r_{2} }^{2} \\ = > \pi( { r_{1} }^{2} - { r_{2} }^{2} ) \\ = > \frac{22}{7} (81 - 25) \\ = > \frac{22}{7} \times 56 \\ = > 176 \: {cm}^{2}$