Question

A circle has area of `36pi` `ft^2`. What is the circumference of the circle?

Answer 1

`12pi`

Explanation:

The formula for the area of a circle is `pir^2` so in this case `pir^2 = 36pi`
`:.r^2 = 36`
`r=6`

The circumference of a circle is given by `2pir` so the circumference is `2pi6 = 12pi`

Answer 2

`12pi`

Explanation:

Remember

`color(brown)(pi=22/7`

Area of circle `=pir^2`

Where `r` is the radius of the circle

So,

`rarr36pi=pir^2`

Cancel `pi` both sides

`rarr36cancelpi=cancelpir^2`

`rarr36=r^2`

`rarrsqrt36=r`

`rarrr=6`

Now we need to find the circumference of circle

Circumference of circle`=2pir`

Substitute the value of `r`

`rarr2pi6`

`color(green)(rArr12pi`