求lim(1-cosx)/x^2
问题描述：
求lim(1-cosx)/x^2
求lim(1-COSX)/X^2
X→0
答
答：
lim(x→0) (1-cosx)/x²
=lim(x→0) 2sin²(x/2)/[4*(x/2)²]
=lim(t→0) (1/2）(sint/t)²
=1/2