Numerically Solve

[Nusc]

I need to solve this implicit function of the catenary

k=cosh(k/sqrt(k^2-1))

how do i Do this in mathematica?

[lurflurf]

FindRoot[k==Cosh[k/Sqrt[k^2-1]], {k,guess}]
Where guess is a guess of the answer.

[Hepth]

If you do a :
Plot[{k, Cosh[k/Sqrt[(k^2 - 1)]]}, {k, 0, 4}]

You can get an approximate guess to use lurflurf's suggestion, for the two roots.
FindRoot[Cosh[k/Sqrt[k^2 - 1]] - k, {k, 0.6}]
FindRoot[Cosh[k/Sqrt[k^2 - 1]] - k, {k, 2}]