如何化简sin(x-π/2) cos(x+π/2) cos(x+3π/2)

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如何化简sin(x-π/2) cos(x+π/2) cos(x+3π/2)

如何化简sin(x-π/2) cos(x+π/2) cos(x+3π/2)
如何化简sin(x-π/2) cos(x+π/2) cos(x+3π/2)

如何化简sin(x-π/2) cos(x+π/2) cos(x+3π/2)
sin(x-π/2)=-cosx
cos(x+π/2) =-sinx
cos(x+3π/2)=sinx

Sin(x-π/2)=-Sin(π/2-x)=-cosx cos(x+π/2)=-cos(π-x-π/2)=-cos(π/2-x)=-sinx
cos(x+3π/2)=cos(x+3π/2-2π)=cos(x-π/2)=cos(π/2-x)=sinx