这个是1的无穷型,解法是用e换底
L= lim(x->0) (cosx)^(1/ln(1+x^2))
lnL = lim(x->0) lncosx/ln(1+x^2) (0/0)
= lim(x->0) -(1/cosx)sinx/ [2x/(1+x^2)]
= lim(x->0) -(1+x^2)sinx / (2xcosx) (0/0)
=lim(x->0) -[(1+x^2)cosx +2xsinx]/(2(-xsinx+cosx))
=-1/2
L = e^(-1/2)