问题描述: lim(x趋向于0)(1-cosx)/x^2 1个回答 分类:数学 2014-10-12 问题解答: 我来补答 倍角公式:cosx=1-2[sin(x/2)]^2故1-cosx=2[sin(x/2)]^2于是lim x->0 (1-cosx)/x^2=lim x->0 2[sin(x/2)]^2/x^2=lim x->0 2[(sin(x/2)/(x/2)]^2*1/4=lim x->0 1/2*[(sin(x/2)/(x/2)]^2=1/2 展开全文阅读