Question

求lim(x->0+) x/[根号(1-cosx)]的极限,

Answer 1

因为1-cosx等价于x^2/2,所以

lim(x->0+) x/[根号(1-cosx)]

=lim(x->0+) x/√(x^2/2)

=1/√1/2

=√2