lim (x/cotx - π/2cosx)
=lim (xsinx/cosx - π/2cosx)
=lim ([xsinx-(π/2)]/cosx) 属于0/0型,洛必塔法则
=lim ([sinx+xcosx]/(-sinx)) 代入x=π/2
=1/-1=-1
lim (x/cotx - π/2cosx)
=lim (xsinx/cosx - π/2cosx)
=lim ([xsinx-(π/2)]/cosx) 属于0/0型,洛必塔法则
=lim ([sinx+xcosx]/(-sinx)) 代入x=π/2
=1/-1=-1