Show-that-when-x-is-small-ln-cosh-x-x-2-2-x-4-12-and-that-when-x-is-large-ln-cosh-x-x-ln-2-

Question Number 178358 by Spillover last updated on 15/Oct/22

Show that when x is small

\ln (\cosh x) \approx \frac{x^{2}}{2} - \frac{x^{4}}{12} + \dots and

that when x is large \ln (\cosh x) \approx x - \ln 2