典型的0/0型,罗比达即可
分子求导得到-0.5(1-x^2)^(-1/2) * (-2x) = x(1-x^2)^(-1/2) = 0
分母求导得到e^x+sinx =1
显然极限是 0/1=0(1-y)^(1/2)~ 1-y/2, e^x~1+x, cosx = 1-x^2/2所以 [1-(1-x^2)^1/2]/(e^x-cosx)~ [1-(1-x^2/2)]/(1+x-1+x^2/2) = x^2/2 /x(1+x/2) ~ x^2/2x = x/2 ~0