Question

cos (α +П/6 ), если cos α = 0,6;
3п /2 < α < 2п

Answer 1

cos (α +π/6 )=cosα*(cosπ/6)-sinα*(sinπ/6)

α∈4 четверти, поэтому sinα=-√(1-cos²α)=-√(1-0/36)=-0.8

cos (α +π/6 )=0.6*(√3/2)-(-0.8)*(1/2)=0.3√3+0.4