Hyperbolic cosine function needed for a building. HELP!!?

There is a building which has the same shape as the ST LOUIS ARCH (KINDA UPSIDE DOWN "U"). i NEED TO model a function for this building. The dimensions of the base of the building are 150 x 72 m. The facade (the front part/main entrance) of the building is on the shorter side i.e. 72 m. Now, my teacher has told me to use a catenary function (a type of hyperbolic cosine function). How do I find this function. Also the height of the building is 36 m..but we will investigate the change. Hence, the function should be in terms of height (h).

YOUR HELP IS APPRECIATED :D THANKS :)Hyperbolic cosine function needed for a building. HELP!!?
i am not sure if we have all the dimensions to form an equation

the mathematical equation for saint louis gateway arch as shown in the architecture blueprints are provided by dr H bandel



the following are calculated based on the data from saint louise gateway arch

A = f / [ (qb/qt) - 1 ] = 68.77ft

C = acosh(qb/qt) = 3.00ft

qb = 1262.67ft max cross-section area of the arc at the base

qt = 125.14ft min cross-section area of the arc at the top

f = 625ft max height of centroid

L = 299ft half width of centroid at the base



a = A + f

b = A

c = C / L

the equation of the arch

y = a - b * cosh(c * x)

y = 693.86 - 68.77 * cosh(0.010x) %26lt;== ans



compare above calculation with your known data of the bldg

the function is plotted on x-y graphHyperbolic cosine function needed for a building. HELP!!?
READ MATHEMATICAL DESCRIPTION SECTION IN FOLLOWING LINK:

http://en.wikipedia.org/wiki/Catenary

hope it will help a bit.