is the answer
edit: oops I maybe wrong
That was what I got, hope it's right.
I used the basic proof for integration of sine (x), but subbed x with 1/x. That is, to find dy/dx, find dx/dy and flip it the other way. Then, I replaced the 'cos^2(y)' and 'sine y' in the final answer with x (by replacing cos y with sqr root (1 - sine^2(y))
Sorry if I confused anyone :l
EDIT: Or you could simply use the function within a function rule. Inverse sine f(x) = f'(x)*(1/sqr root (1-x^2) where f'(x) in this case is -1/x^2