y=sin²x+√3 sinxcosx - 1
=(1/2)(1-cos2x)+(√3/2)sin2x-1
=(√3/2)sin2x-(1/2)cos2x-1/2
=sin(2x-π/6)-1/2
所以y最小=-1-1/2=-3/2
y最大=1-1/2=1/2
故值域为[-3/2,1/2]=(1/2)(1-cos2x)+(√3/2)sin2x-1=(√3/2)sin2x-(1/2)cos2x-1/2这步是怎么来的?3Q上一步是倍角公式cos2x=1-2sin²xsin2x=2sinxcosx下一步是直接化简