Question 33720
Consider the shape of y=(-1/2)x^2+27, which has the same shape
as yours.  Find the x-intercepts to determine the radius of
the building, as follows:
(1/2)x^2=27
x^2=54
x=radius=sqrt27
Then Volume = (1/2)(pi)(radius)^2(height)
V= (1/2)(pi)54(27)
V=27^2(pi)
Volume=729pi cu.ft.
Cheers,
Stan H.