Question

If the radii of two concentric circles are $15cm$ and $13cm$ respectively then the area of the circulating ring in sq cm will be

• A. $176$
• B. $178$
• C. $180$
• D. $200$

Answer 1

The correct option is A $176$

$R=15cm,r=13cm$
Area of the circulating ring
$=\pi (R^2-r^2)$

$=\pi (R+r)(R-r)$
$=\frac{22}{7}(15+13)\times (15-13)$
$\frac{22}{7}\times 28\times 2$
$=176$ sq cm