Wha is the total surface area of the tower?
Let's get the top and bottom surface areas first
t=pi r^2 = pi (18^2) = 1017.876
b=pi r^2 = pi (36^2) =4071.504 (IF we are counting the bottom)
the 'Middle surface area is just the difference betwen these two 4071.504 - 1017.876 = 3053.628
Now the sides are pi x d x h
Bottom pi x 72 x 18 =4071.504
top pi x 36 x 18 = 2035.752
Now add them all together:
2035.752 + 4071.504 + 3053.628 + 4071.504 + 1017.876 = USE calculator
NOTE: IF BOTTOM is not cosidered part of the 'Surface Area' leave out ONE of the 4071.504 terms.
(14250.264 sq in)