sinαcosβ=12[sin(α+β)+sin(α−β)] sin\alpha cos\beta = \frac{1}{2}[sin(\alpha+\beta) + sin(\alpha - \beta)] sinαcosβ=21[sin(α+β)+sin(α−β)] cosαsinβ=12[sin(α+β)−sin(α−β)] cos\alpha sin\beta = \frac{1}{2}[sin(\alpha+\beta)- sin(\alpha - \beta)] cosαsinβ=21[sin(α+β)−sin(α−β)] cosαcosβ=12[cos(α+β)]+cos(α−β)] cos\alpha cos\beta = \frac{1}{2}[cos(\alpha+\beta)] + cos(\alpha - \beta)] cosαcosβ=21[cos(α+β)]+cos(α−β)] sinαsinβ=−12[cos(α+β)−cos(α−β)] sin\alpha sin\beta = -\frac{1}{2}[cos(\alpha+\beta) - cos(\alpha - \beta)] sinαsinβ=−21[cos(α+β)−cos(α−β)]
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