This stuff confuses me! will ba

find the circumference of a circular disk whose area is 100 pi square centimeters.

So, this is kinda similar to the other I helped you with:

So r is the radius of the disk. The area is known and equal to 100Pi; so 

100Pi = Pi r2

Now for r: r = 10 

Circumference = 2 PI r = 20 Pi

I hope this helped!

100Pi = Pi r2
 r = 10 
Circumference = 2 PI r = 20 Pi

108