what is the answer of " integral of squar root of sin x dx " ?

Answer 1

So sorry! This integral cannot be evaluated in terms
of elementary functions. It is an elliptic integral
of the second kind.
The first answer you got is wrong. The mistake
was trying to use the power rule where it
is not applicable. You can only use it that way
for powers of x, nothing else!

Answer 2

(-2/3) (cosx^(3/2))

its rea;lly easy to see if you differentiate this but il let you gfigure out how to intergrate