Okay so the equation you need to use is (x2/a2)+(y2/b2)-(z2/c2)=1
So an equation describing the shape of the tower in the coordinates where the origin is at the center of the narrowest part of the tower would be:
x^2 / 100^2 + y^2 / 100^2 – z^2 / 2 * 100^2 = 1
I am hoping that this answer has satisfied your query and it will be able to help you in your endeavor, and if you would like, feel free to ask another question.