The equation for the circumference of a circle is

, where C=circumference and r=radius of the circle.
You are told that the circumference is 16.502. Plug this into the equation for circumference to find the value of r, the radius:

.
Now you know that r =

. The equation for the area of a circle is

, where A = area and r = radius of the circle.
Since you know the radius, r =

, plug that into the equation for area and solve for the area of the circle:

The area of the circle is about 21.670.