Let u sin(x) then du = cos(x) dx
you obtain integral ( du/(1+u^2)) = arctan(u) + C = arctan(sin(x))+C
alex83 - You have posted a few of the same types of problems with trig integrals. Why don't you try to finish one and understand it completely before asking for help on another? Do you get the basic concepts behind these? I want you to be able to do them on a test without our help is all.