f(x)=sinx＋√3cosx
=2[sinxcos60°＋cosxsin60°】
=2sin(x＋π/3).
值域是[－2,2].=2[sinxcos60°＋cosxsin60°怎么得来得啊？f(x)=2[(1/2)sinx＋(√3/2)cosx]而cosπ/3=1/2，sinπ/3=√3/2所以f(x)=2[sinxcosπ/3＋cosxsinπ/3]=2sin(x＋π/3)