can tell when function has inverse
sin(x) limit domain so no repeat y val from $$[frac{-\pi}{2}, \frac{\pi}{2}] $$
to isolate y, you take arcsin
get y=arcsin(x)
range becomes domain and vice versa
sin domain is [1,-1]
cos would need to be in the first and needs to have all possible values
would be from $$[0,\pi]$$
tan limit domain is then $$[\frac{-pi}{2}], \frac{\pi/2}{2} ]$$