There are two ways to enter mathematical symbols. The first is, to use the panel with mathematical symbols on the right side of the screen. The second is, to type keywords which often is a more efficient way once you get familiar with the names of the commands. The keywords specifically chosen to be intuitive. Also pointing mouse at a symbol in the panel will give you a hint for the specific keyword.

Some of the useful shortcuts:

^ -- raise to a power.

sqrt -- create a root symbol

int -- create an integral sign

pi -- create the greek letter

arcsin, arccos, arctan -- inverse trigonometric functions

po -- create (,) notation for a point

(,) -- create notation for an interval