Question

X趋于零，1-cosx的和除以x的极限是多少，怎么化简

Answer 1

...洛必达法则，分子分母同时求导
1-cosx 洛必达 sinx
---------- ========> ---------- =0
x 1

Answer 2

1-cosx=2(sin(x/2))^2
lim 2(sin(x/2))^2/x=lim 2sin(x/2)/x *lim sin(x/2) =1*0=0