Why aren't my catenary equations matching up?

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I have a cable suspended between two poles, both $1086.4$ ft high, that are $4444.7$ ft apart. The sag at the middle of the cable is $197.8$ ft. Given this, the constant should be $c = 1086.4 - 197.8 = 888.6$. However, when I try to use that $c$ in any equations, my results come out completely wrong.

Ex: $y=c \cosh\frac{x}{c}$

For the y at the pole/end,

$c \cosh\frac{x}{c} = 5454$

which is obviously very off from the pole's actual height of $1086.4$.

What am I doing wrong?

(I've looked through the following resources for help but haven't been able to find a formula/definition for c that comes close to my actual values. http://www.ce.siue.edu/examples/Worked_examples_Internet_text-only/Data_files-Worked_Exs-Word_&_pdf/cables_catenaries.pdf

http://euclid.trentu.ca/aejm/V4N1/Chatterjee.V4N1.pdf

http://www.stem2.org/je/catenary.pdf)