求最小正周期.y=2sinx-cosx y=sin^4x-cos^4x y=2根号3cosxsinx-cos^2x-1

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求最小正周期.y=2sinx-cosx y=sin^4x-cos^4x y=2根号3cosxsinx-cos^2x-1
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求最小正周期.y=2sinx-cosx y=sin^4x-cos^4x y=2根号3cosxsinx-cos^2x-1
求最小正周期.y=2sinx-cosx y=sin^4x-cos^4x y=2根号3cosxsinx-cos^2x-1

求最小正周期.y=2sinx-cosx y=sin^4x-cos^4x y=2根号3cosxsinx-cos^2x-1
y=2sinx-cosx=√5sin(x-θ)
T=2π/1=2π
y=sin^4x-cos^4x=(sin^2x+cos^2x)(sin^2x-cos^2x)=-cos2x
T=2π/2=π
y=2√3cosxsinx-cos^2x-1=√3sin2x-cos2x/2-3/2=√13/2sin(2x-θ)-3/2
T=2π/2=π