解法一：等价无穷小 lim sinx/sin3x x→0 =lim x/(3x) x→0 =⅓ 解法二：洛必达法则 lim sinx/sin3xx→0 =lim cosx/(3cos3x) x→0 =cos0/(3·cos0) =1/(3·1) =⅓
