（1+√3tanα）(1+√3tanβ)=41+3tanαtanβ+√3(tanα+tanβ)=4tan(α+β)=(tanα+tanβ)/(1-tanαtanβ)而tanαtanβ=[3-√3(tanα+tanβ)]/3代入,化简即可sinθ-cosθ=1/5平方1-sin2θ=1/25sin2θ=24/25cos2θ=根...