令√x = t,则x→0时,t→0原式= lim (cost)^(π/t²)=lim (1 + (cost-1) )^(π/t²)=lim (1 + (cost-1) )^(1/(cost-1) * (cost-1)π/t²)=lim ( (1 + (cost-1) )^(1/(cost-1)) )^ (cost-1)π/t²)注...