Question

Calculate the area of a circular ring whose outer and inner radii are $12$ and $10cm.$

• A. $118.16$ $c{m}^2$
• B. $128.16$ $c{m}^2$
• C. $138.16$ $c{m}^2$
• D. $148.16$ $c{m}^2$

Answer 1

The correct option is C $138.16$ $c{m}^2$

Area of a circular ring $=\pi (R^2-r^2)$
$=3.14({12}^2-{10}^2)$
$=3.14\times 44$
$=138.16$ $c{m}^2$