To calculate the area of a circle, use the equation a=pir^2 or area=3.14*radius squared
Insert the known values. We need to find the radius of the circle. Since the radius is half of the diameter, divide the diameter by 2 to get the radius.
The diameter is 20.
20/2=10
Area=3.14*10 squared
Area=3.14*100
Area=314 cm
Hope this helps!