作业帮已知集合A={x|π/4
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已知集合A={x|π/4
已知集合A={x|π/4
已知集合A={x|π/4
f(x)=4sin^2(π/4+x)-2√3cos2x-1
f(x)=2[1-cos(π/2+2x)]-2√3cos2x-1
=2sin2x-2√3cos2x+1
=4sin(2x-π/3)+1
π/4
f(x)=4sin^2(π/4+x)-2√3cos2x-1
f(x)=2[1-cos(π/2+2x)]-2√3cos2x-1
=2sin2x-2√3cos2x+1
=4sin(2x-π/3)+1
π/4<=x<=π/2
π/6<=2x-π/3<=2π/3
1/2<=sin(2x-π/3)<=1
故4*1/2+1<=f(x)<=4*1+1
即值域是[3，5]
求采纳