Question

Find the area and inner circumference of the ring.

• A. $9.48$ sq. cm, $3.14$ cm
• B. $9.42$ sq. cm, $6.48$ cm
• C. $9.42$ sq. cm, $2.14$ cm
• D. None of these

Answer 1

Answer: (B)

$9.42$ sq. cm, $6.48$ cm

Area of a circular ring = $\pi (R^2-r^2)$
$=$ $3.14(2^2-1^2)$
$=3.14\times 3$
$=9.42$ sq. cm
Inner circumference $=$ $2\pi r$
$=2\times 3.14\times 1$
$=6.28$ cm