=e^ lim (1/1-cosx)·ln（sinx/x）=e^ lim ln（sinx/x）/(1-cosx)=e^ lim (sinx/x -1）/(x²/2)=e^ lim 2(sinx-x)/x³=e^ lim 2(cosx-1)/(3x²)=e^ lim 2(-x²/2)/(3x²)=e^(-4/3)