Question

The circumference of a circle whose area is 81πr2, is ________

Answer 1

Answer:

18π

Step-by-step explanation:

Given area of a circle is 81π.

We know formula for area of a circle is πr2

So,πr2=81π

⇒r2=81

⇒r=9

Formula for circumference is 2πr.

So putting r=9 circumference will be

2π9=18π