tan(π/4+α)×cos2α/2cos²(π/4-α)其中cos2α=sin(π/2-2α）=2sin(π/4-α）cos(π/4-α）带入原式得tan(π/4+α)× tan(π/4-α)=1其中tan(π/4+α)=【tan(π/4）+tan(α)】/【1-tan(π/4）*tan(α)】=【1...