f(x)=2[sin(π/3)cos(3x-θ)-cos(π/3)sin(3x-θ)]=2 sin(π/3-3x+θ)
为奇函数,须满足：
π/3+θ=kπ,k为任意整数
tanθ=tan(kπ-π/3)=-tanπ/3=-√3π/3+θ=kπ 怎么来的啊因为sinx为奇函数，sin(x+kπ)为奇函数。谢谢了