0≤|x·sin(π/tanx)|≤正乱|x|∵lim(x→0)0=0lim(x→歼清巧0)|x|=0∴lim(x→0)|x·sin(π/氏键tanx)|=0∴lim(x→0)x·sin(π/tanx)=0
有界乘以无穷小，结果0
