α+β=π/2所以β=π/2-αtanα+tanβ=4故tanα+tan(π/2-α)=4即tanα+cotα=tanα+1/tanα=4所以(tanα)^2-4tanα+1=0所以tanα=[4±√(16-4)]/2=2±√3所以α=arctan(2+√3),β=arctan(2-√3)或α=arctan(2-√3),...