50 пкт за правильное cos(arctg(1/3)+ arctg (-√3)

Cos(arctg(1/3)-arctg(√3))=cos(arctg(1/3)cos60+sin60sin(arctg(1/3))=
tgx=1/3
sin^2x/cos^2x=1/9
9sin^2x=1-sin^2x
sinx=√10/10
cosx=3√10/10

=3√10/20+√30/20=√30/20(√3+1)