∵sinαcosβ+cosαsinβ=sin（α+β）=12+cosαsinβ，∴-1≤12+cosαsinβ≤1即-32≤cosαsinβ≤12∵sinαcosβ-cosαsinβ=sin（α-β）=12-cosαsinβ，∴-1≤12-cosαsinβ≤1即-12≤cosαsinβ≤32∴-12≤cos...