sin(α-β)怎么用cos(α-β)\cos(α+β)推导
问题描述：
sin(α-β)怎么用cos(α-β)\cos(α+β)推导
答
已知：cos (α +β) = cos α cos β -sin α sin β,sin (π/2 -α) =cos α, cos (π/2 -α) =sin α.则sin (α -β) =cos [ π/2 -(α -β) ] =cos [ (π/2 -α)+β ] =cos (π/2 -...