The graph of
is shown below.
So we'll basically want to find the domain and range of the function we're given. The domain will be of the form

and the range will be

, which allows us to find out answers.
We can look at the inverse sine function without any transformations, and then look at what transformations have be done to the function we've given.
So as Haters pointed out, we can find b quite easily.
+1 = 2\frac{-\pi}{2} + 1 = 1 - \pi)
We know the domain and range of inverse sine (yay spesh formula sheet):
Domain of arcsin(x):

Range of arcsin(x):

So domain of y:
-1] = [0,1])
which means a = 1
Range of y: Well instead of looking at this from the point of view of transformations, we can sub in our domain values now, which we can see will be an okay thing to do looking at the graph and noting that it's increasing.
+1, 2arcsin(2-1)+1] = [1 - \pi,2arcsin(1)+1] = [1 - \pi,2\frac{\pi}{2}+1] = [1 - \pi,1 + \pi])
So

and
