2+2cosx=2(1+cosx)=2(cos^2x/2+sin^2x/2+cos^x/2-sin^2x/2)=
=4cos^2x/2
sinx/2cosx/2=2(sinx/2cosx/2)/2(cosx/2)=sinx/2
∫sin(x/2)dx=-2cosx/2
