Mathematica forms of notations
Following Mathematica's general naming convention, function names in StandardForm are just the capitalized versions of their traditional mathematics names. This shows the cotangent function in StandardForm.
This shows the cotangent function in TraditionalForm.
Additional forms of notations
Mathematica has other popular forms of notations that are used for print and electronic publication. In this particular instance the task is not difficult. However, it must be made to work in Mathematica's CForm, TeXForm, and FortranForm.