Dear sir please find the answer which I have mentioned above...

let  sin^-1  (1-x) = A  ,   So  Sin A  = 1-x
let  Sin^-1 x = B,     So Sin B = x 

Given   A - 2 * B = π/2
            A  - π/2  = 2B
           Cos (A - π/2)  = Cos (2 B)
           Sin A =  1 - 2 Sin² B 
           1 - x   = 1 - 2 x² 
           2 x² - x = 0
           x = 0 or   x = 1/2