The area of a circle is 81π m². What is the circumference, in meters? Express your answer in terms of π.

Step-by-step explanation:

to find the circumference we need to find the radius of the circle.

For this, we use the formula for the area :

where is the area, is a constant and is the radius.

we know that the area is:

so we substitue this into the previous formula:

and we solve for   :

the radius is 9 meters.

Now we use the formula for circumference of a circle:

and substitute the value that we've just found for r:

the answer in terms of is meters is the circumference