asin(θ+α)=bsin(θ+β)a(sinθcosα+cosθsinα)=b(sinθcosβ+cosθsinβ)asinθcosα+acosθsinα=bsinθcosβ+bcosθsinβ移项asinθcosα-bsinθcosβ=bcosθsinβ-acosθsinαsinθ(acosα-bcosβ)=cosθ(bsi...