y= arcsinx .√[(1-x)/(1+x)]
y' = (1/2)√[(1+x)/(1-x)]. [-2/(1+x)^2] . arcsinx + √[(1-x)/(1+x)] . [1/√(1-x^2)]
= -√[1/[(1-x)(1+x)^3] . arcsinx + 1/(1+x)
= [1/(1+x)] ( 1- arcsinx. √ [1/(1-x^2)] )