令x = π/2 - t,dx = - dt当x = 0,t = π/2,当x = π/2,t = 0L = ∫(0-->π/2) e^sinx/(e^sinx + e^cosx) dx= ∫(π/2-->0) e^sin(π/2 - t)/[e^sin(π/2 - t) + e^cos(π/2 - t)] · - dt= ∫(0-->π/2) e^cost/(e^...