Hello, I am to evaluate the real part of  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  sin^-^1 z =  \frac{1}{i} ln [ i (z) + \sqrt {1- z^2}  ]

i then substitute the values for z

 sin^-^1 z =  \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