sinαcosβ=(1/2)[sin(α+β)+sin(α-β)]；cosαsinβ=(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)].2sin(α+β)/2*cos(α-β)/2=sinα+sin...