Question

the circumference of a circle is 3.1 metre find its area

Answer 1

the circumference of a circle equal to 3.1 metre the formula of the circumference of a circle is 2πr when we put 2πr equal to 3.1
we get,
2πr= 3.1
2×3.1×r=3.1
r =3.1/ 3.1×2
r= 0.5
then by the formula of area
$\\\pi {r}^{2}$
putting the values,

$3.1 \times {0.5}^{2}$
7.5

Answer 2

circumference of circle = 3.1
To find the Area of circle first we find the radius of circle.
So, Let be the radius of circle = r

Cirumference of circle =
$2\pi \: r$
$3.1 = 2 \times \frac{22}{7} \times r$
$3.1 = \frac{44}{7} \times r$
$3.1 \times \frac{7}{44} = r$
$\frac{10.85}{22}$
$0.49$
So , the radius of circle = 0.49

Area of circle =
${\pi \: r}^{2}$
$= \frac{22}{7} { \times 0.49}^{2}$
$= \frac{22}{7} \times 0.2401$
$= 22 \times 0.0343$
$= 0.7546$
$so \: the \: area \: of \: circle \: = {0.7546m}^{2}$