怎样将cos转换为sin?y=100cos(2π/364)+1140,如何将COS的式子转为SIN?急.

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怎样将cos转换为sin?y=100cos(2π/364)+1140,如何将COS的式子转为SIN?急.怎样将cos转换为sin?y=100cos(2π/364)+1140,如何将COS的式子转为SI

怎样将cos转换为sin?y=100cos(2π/364)+1140,如何将COS的式子转为SIN?急.
怎样将cos转换为sin?
y=100cos(2π/364)+1140,如何将COS的式子转为SIN?急.

怎样将cos转换为sin?y=100cos(2π/364)+1140,如何将COS的式子转为SIN?急.
因为:sin²α+cos²α=1
所以:cos²α=1-sin²α
因此:cosα=±√(1-sin²α)
因为:0<2π/364<π/2
所以:cos(2π/364)>0
因此:cos(2π/364)=√[1-sin²(2π/364)]
y=100cos(2π/364)+1140
y=100√[1-sin²(2π/364)]+1140
y=100√[1-sin²(π/182)]+1140

cos(π/2-θ)=sin(θ),故y=100cos(2π/364)+1140=100sin(45π/91)+1140

cos2α=1-2sin²α
cos(2πx/364)=1-2sin²(πx/364)
y=100-200sin²(πx/364)+1140=1250-200sin²(πx/364)