### Standard Functions (sin, cos etc.)

The names of certain standard functions and abbreviations are
obtained by typing a backlash `\`

before the name.
For example, one obtains

by typing
\[ \cos(\theta + \phi) = \cos \theta \cos \phi
- \sin \theta \sin \phi \]

The following standard functions are represented by control sequences
defined in LaTeX:

Names of functions and other abbreviations not in this list can be
obtained by converting to the roman font. Thus one obtains
by typing `$\mathrm{cosec} A$`

.
Note that if one were to type simply `$cosec A$`

one
would obtain
because LaTeX has treated
`cosec A`

as the product of six quantities
*c*, *o*, *s*, *e*, *c* and *A*
and typeset the formula accordingly.