已知a(sinx,-cosx),b(cosx,根号3cosx)f(x)=ab+(根号3/2),求f(x)最小正周期,当0

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已知a(sinx,-cosx),b(cosx,根号3cosx)f(x)=ab+(根号3/2),求f(x)最小正周期,当0
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已知a(sinx,-cosx),b(cosx,根号3cosx)f(x)=ab+(根号3/2),求f(x)最小正周期,当0
已知a(sinx,-cosx),b(cosx,根号3cosx)f(x)=ab+(根号3/2),求f(x)最小正周期,当0<=x<=π/2,求函数值域

已知a(sinx,-cosx),b(cosx,根号3cosx)f(x)=ab+(根号3/2),求f(x)最小正周期,当0
f(x)=ab+√3/2
=sinxcosx-√3cos²x+√3/2
=1/2sin2x-√3/2(2cos²x-1)
=1/2sin2x-√3/2cos2x
=sin(2x-π/3)
f(x)最小正周期T=2π/2=π
∵0≤x≤π/2
∴0≤2x≤π
∴-π/3≤2x-π/3≤2π/3
∴-√3/2≤sin(2x-π/3)≤1
∴f(x)的值域为[-√3/2,1]

f(x)=sinxcosx-√3cos²x+√3/2
=1/2sin2x-√3/2(1+cos2x)+√3/2
=1/2sin2x-√3/2cos2x
=sin(2x-π/3)
最小正周期T=2π/2=π
0≤x≤π/2
∴-π/3≤2x-π/3≤2π/3
∴-√3/2≤sin(2x-π/3)≤1
即值域为[-√3/2,1]