integral cosx/sqrt(cos2x) dx
=integral cosx/sqrt(1-2sin^2x0 dx
dividing by cos^2x in num.and denom. both,we get
integral sec^2x dx/sqrt(sec^2x-2tan^2x)
=integralsec^2xdx/sqrt(1+tan^2x-2 tan^2x)
=integral sec^2x dx/sqrt(1-tan^2x)
put tanx=t
on diff. w.r.t. x we get sec^2xdx=dt
=integral dt/sqrt(1-t^2)
=arcsin(t)
=arcsin(tanx)
Thanks & Regards
Rinkoo Gupta
AskIITians Faculty