f(x)
＝sinx－√3cosx
＝2(sinx•1/2－cosx•√3/2)
＝2sin(x－π/3)
由：－π/2＋2kπ≤x－π/3≤π/2＋2kπ
得：－π/6＋2kπ≤x≤5π/6＋2kπ
∵x∈[－π,0]
取交集,得：[－π/6,0]