Question

Find the radius of a circle with an area of 308cm²

Answer 1

Answer:

Step-by-step explanation:

r≈9.9

A Area=  

308

Using the formula

A=πr2

Solving for

r=9.9

Answer 2

Given,

The area of circle is 308cm².

To find out,

The radius of the circle.

Solution:

$Area \: of \: circle \: = \: \pi {r}^{2}$

$308 = \frac{22}{7} \times {r}^{2}$

$\frac{308 \times 7}{22} = {r}^{2}$

$\frac{2156}{22} = {r}^{2}$

$98 = {r}^{2}$

$r \: = \sqrt{98}$

$r = 9.9$

Therefore the radius of the circle is 9.9 cm.

Proof:

$Area \: of \: circle \: = \: \pi {r}^{2}$

$Area \: of \: circle = \frac{22}{7} \times {(9.9)}^{2}$

$Area \: of \: circle = \frac{22}{7} \times 98$

$Area \: of \: circle = 22 \times 14$

$Area \: of \: circle = 308 {cm}^{2}$

Additional information:

Formulae:

$Area \: of \: circle \: = \: \pi {r}^{2}$

$radius \: of \: circle \: = \sqrt{ \frac{area}{ \pi} }$

$diameter \: of \: circle \: = 2r$

$circumference \: of \: circle \: = 2 \pi \: r$