(cosβ-a)sin(α+β)
=cosβsin(α+β)-asin(α+β)
=cosβsin(α+β)-sinα
=1/2*(sin(α+2β)+sinα)-sinα
==1/2*(sin(α+2β)-sinα)
=cos(α+β)sinβ
两边除以cos(α+β)*(cosβ-α)得:
tan(α+β)=sinβ/(cosβ-α)
(cosβ-a)sin(α+β)
=cosβsin(α+β)-asin(α+β)
=cosβsin(α+β)-sinα
=1/2*(sin(α+2β)+sinα)-sinα
==1/2*(sin(α+2β)-sinα)
=cos(α+β)sinβ
两边除以cos(α+β)*(cosβ-α)得:
tan(α+β)=sinβ/(cosβ-α)