If I wanted to obtain Sin^-1(0.5) what would be the proper command
or to get an exact answer use
A reminder: The Documentation Center is your friend.
If you go to the documentation for Sin and scroll down to the bottom to the list of other functions under the heading "See Also" you will see a link to ArcSin.
Also if you were to type arcsin into the Documentation Center search bar, the first item that comes up is the link to that same documentation.