sin(-θ)=-sinθ, cos(-θ)=cosθ, tan(-θ)=-tanθ
sin²θ+cos²θ=1, sec²θ-tan²θ=1, csc²θ-cot²θ=1
sin(π/2-θ)=cosθ, sin(π/2+θ)=cosθ, sin(θ±π/2)=±cosθ
cos(π/2-θ)=sinθ, cos(π/2+θ)=-sinθ, cos(θ±π/2)=Ŧsinθ
sin(π-θ)=sinθ, sin(π+θ)=-sinθ, sin(θ±π)=-sinθ
cos(π-θ)=-cosθ, cos(π+θ)=-cosθ, cos(θ±π)=-cosθ
sin(α±β)=sinαcosβ±cosαsinβ, cos(α±β)=cosαcosβŦsinαsinβ
tan(α+β)=tanα+tanβ/1-tanαtanβ, tan(α-β)=tanα-tanβ/1+tanαtanβ
sin2θ=2sinθcosθ
cos2θ=cos²θ-sin²θ=2cos²θ-1=1-2sin²θ, tan2θ=2tanθ/1-tan²θ
sin²θ/2=1-cosθ/2, cos²θ/2=1+cosθ/2, tan²θ/2=1-cosθ/1+cosθ
sinαcosβ=1/2{sin(α+β)+sin(α-β)}
cosαcosβ=1/2{cos(α+β)+cos(α-β)}
sinαsinβ=-1/2{cos(α+β)-cos(α-β)}
sinα+sinβ=2sin(α+β/2)cos(α-β/2)
sinα-sinβ=2cos(α+β/2)sin(α-β/2)
cosα+cosβ=2cos(α+β/2)cos(α-β/2)
cosα-cosβ=-2sin(α+β/2)sin(α-β/2)
Pumped from <http://ohhan.com/82>
