lim(x趋向于0)(x*cotx-1)/(x^2)

lim(x-->0)(x*cosx/sinx-1)/x^2=lim(x-->0)(xcosx-sinx)/(x^2sinx)=lim(x-->0)(cosx-xsinx-cosx)/(2xsinx+x^2cosx)=lim(x-->0)(-sinx)/(2sinx+xcosx) (罗比达）=lim(x-->0)(-cosx)/(2cosx+cosx-xsinx) （罗比达）=li...