f(x)=cos(3x+π/3)x∈[π/6,m], f(x)的值域=[-1,-√3/2]Solution:cos(3x+π/3)=-13x+π/3 =3π/2 x=7π/18cos(3x+π/3)=-√3/23x+π/3=5π/3x=4π/9iem≥ 4π/9
