hi ,
take,
y =sin-1(√(x-ax)-√(a-ax))
sin y = √(x-ax)-√(a-ax)
d/dx (sin-1 x) = 1/√(1-x2 )
so ,
d/dx (sin-1(√(x-ax)-√(a-ax))) = 1/√(1-(√(x-ax)-√(a-ax)2) * [-a/2 (1+lnx)*√(x-ax) +(a/2*lna* √(a-ax)]
= -½ a [(1+lnx)√(x-ax)-(lna √(a-ax )] /√(1-(√(x-ax)-√(a-ax)2)
I think no further simplification possible !