Hello, I am to evaluate the real part of $\displaystyle sin^-^1 z = 0.5 (\sqrt{ x^2 +y^2 +2x+1} - \sqrt {x^2 +y^2 -2x+1} $

can someone demonstrate how the identity $\displaystyle sin^-^1 z $ =$\displaystyle \frac{1}{i} ln [ i (z) + \sqrt {1- z^2} ] $

i then substitute the values for z

$\displaystyle sin^-^1 z $ =$\displaystyle \frac{1}{i} ln [ i (x+iy) + \sqrt {1- (x+iy)^2} ] $

beyond there am in a world of trouble any help guys separating into the real parts to get the ans