Question

The area of a circle is 49 $\pi$ $c{m}^2$. Its circumference is

(a) 7 $\pi$cm (b) 14 $\pi$cm (c) 21 $\pi$cm (d) 28 $\pi$cm

Answer 1

The area of a circle is found using the formula$Areaofacircle=\pi \times r^2$ T

So the area of your circle is $49\pi$

so:
$49\pi$ = \pi\times r ^2 \)

solve for r; start by dividing each side by $\pi$
$49=r^2$ take the square root of each side:
7 = r

This circle has a radius of 7.

To find the circumference of a circle, use the formula $Circumference=2\pi \times r$ .

Since we solved for the radius by extracting it from the area, we can find the circumference:
$Circumference=2\pi \times r$ [ r=7]
$Circumference=2\pi \times 7$

$Circumference=14\pi$