Question

Area of a circle is 80 cm². Work out the circumference of the circle.

Can someone please help. And tell me how you did it please.

Answer 1

The circumference of circle is: 31.714 cm

Explanation:

Let C be the circumference of the circle

And A be the area of circle

It is given that:

`A = 80cm^2`

We have to find the radius first so that it can be used to find the circumference

The area of circle is given by the formula:

`A = \pi r^2`

Putting the value of area

`80 = 3.14 * r^2\\(80)/(3.14) = r^2\\r^2 = 25.477`

Taking square root on both sides

`√(r^2) = √(25.477..)\\r = 5.0475\ cm`

Now

`C = 2\pi r`

Putting the value of radius

`C = 2 * 3.14 * 5.05\\C = 31.714\ cm`

Hence,

The circumference of circle is: 31.714 cm