limx-01-cosx/x^2=1/2?用恒等变形怎么推呢

2023-04-27

问题描述:

lim x-0 1-cosx / x^2=1/2?
用恒等变形怎么推呢


最佳答案:

1-cosx =1-[1-2sin²(x/2)]=2sin²(x/2)
当x→0时,sin²(x/2) x/2

1-cosx x²/2

lim x-0 1-cosx / x^2=1/2