Answer:
314cm
Explanation:
the area formular for a circle is a=pi(r)^2. Using this information we can plug in the numbers...
3.14(10)^2. Next square 10 to get 3.14*100. Then you get 314 which is the answer. The reason I used 10 is because the diameter is half of the radius so half of 20 would be 10.