inverse function

Do you mean inverse trig?

inverse sin is the same as arc sin. so you'd press 2nd function then asin

It is the same idea for inverse cos and inverse tan.  

Assuming that we have some "one-to-one function" of x = f(x) = "y"

(Note that we might have to "restrict" the domain of the original function in order to produce an "inverse.")

1st, isolate x on one side of the equation

2nd, "switch" (exchange) x and y

3rd, for "y," write f^-1(x)  ...the " f^-1(x)" indicates the inverse function....

That's it, in a nutshell !!

Thanks, Melody.....now that I look at it, I think this is probably what the questioner meant, too. However, we both provided him/her with answers to two different things....that's unusual...!!!

I don't think that is so unusual - we are always guessing what the askers want. lol