lim（x->oo）(x^2+(cosx)^2-1)/(x+sinx)^2=lim（x->oo）(x^2-(sinx)^2)/(x+sinx)^2分子分母同除以xsinx得到：=lim（x->oo）(x/sinx-sinx/x)/(x/sinx+sinx/x+2)=lim（x->oo）(x/sinx+sinx/x+2-2-2sinx/x)/(x/sinx+sin...