cos(x) + 2sin(x)*cos*(x)=0;
cos(x) * (1 + 2sin(x) ) =0;
cos(x)=0 ∨ 1+2sin(x)=0
x=π/2+π*n, n∈Ζ ∨ x=-π/6 + 2πn ∨ x=-5π/6 = 2πn, n∈Ζ
