5.1
2*cos(π/4-3x)=√2
cos(π/4-3x)=√2/2
π/4-3x=+/-π/4
-3x=0 -3x=-π/4-π/4=-π/2
x₁=0 x₂=π/6.
5.2
sinx+√3*cosx=0
sinx=-√3*cosx I÷cosx
tgx=-√3
x=-π/3+πn.
5.3
2*cos²(x/3)+√3*cos(x/3)=0
cos(x/3)*(2*cos(x/3)+√3)=0
cos(x/3)=0
x/3=π/2+πn
x₁=3π/2+3πn
2*cos(x/3)+√3=0
cos(x/3)=-√3/2
x/3=-π/3+πn
x₂=-π+3πn.