硬算2tan2β＝tanα + tanβ所以 tanα=2tan2β-tanβ = 4tanβ/(1-tan^2 β)-tanβ=(3tanβ+tan^3 β)/(1-tan^2 β)左边= tan(α-β)= (tanα - tanβ)/(1+tanα * tanβ)= [(3tanβ+tan^3 β)/(1-tan^2 β) - tan...