原式=∫x/(1+cosX)dx+∫sinX/(1+cosX)dx=∫xsec^2(x/2)d(x/2)-∫1/(1+cosx)d(1+cosx)=∫xd[tan(x/2)]-ln(1+cosx)=xtan(x/2)-∫tan(x/2)dx-ln(1+cosx)=xtan(x/2)+2ln∣cos(x/2)∣-ln2-ln∣cos(x/2)∣+C1=xtan(x/2)+C...