Assuming the cover is exactly the same size as the pool you would use the formula for the area of a circle which is (pi)r^2
In this case we know that the radius is 14 feet so we plug that in for r. We can use 3.14 as an approximation for pi
14^2=196
multiply by 3.14 and you get an area of
615.44
This can change depending upon your estimation for pi.