write denominator : sq root of sinx cosx = 2sinx cosx/2=1/2* (1 - (1- (2sinxcosx)) = 1/2*(1- (sin2x+Cos2x -2sinxcosx) )
write sinx*cosx = 2sinx cosx/2=1/2* (1 - (1- (2sinxcosx)) = 1/2*(1- (sin2x+Cos2x -2sinxcosx) )
=1/2*(1- ( sinx-Cosx) 2 .
so expression becomes: integr of (Sinx + Cos x)/ sq root of 1/2*(1- ( sinx-Cosx) 2, )
now put Sinx- Cosx = 't' => (Cosx + Sinx )dx = dt , => (sinx + Cosx) dx = dt
so exprssion becomes: dt/ sq root of 1/2*(1- t2) = (sq rt of 2)dt/sq rt of (1-t2) = (sq rt of 2) *sin -1(t) +C
(In my earlier comment i forgot to considr sq root)
Now put t = Sinx - Cosx in this result & get the answer.