The names of certain standard functions and abbreviations are
obtained by typing a backlash
\ before the name.
For example, one obtains
The following standard functions are represented by control sequences defined in LaTeX:\[ \cos(\theta + \phi) = \cos \theta \cos \phi - \sin \theta \sin \phi \]
Names of functions and other abbreviations not in this list can be
obtained by converting to the roman font. Thus one obtains
Note that if one were to type simply
$cosec A$ one
because LaTeX has treated
cosec A as the product of six quantities
c, o, s, e, c and A
and typeset the formula accordingly.