limx-0 sin3x/sin5x=limx-0 [(sin3x/3x)*3x]/[(sin5x/5x)/5x]=limx-0 [(sin3x/3x)*3x]/[(sin5x/5x)/5x]=3/5limx-0[ (sin3x/3x)/(sin5x/5x)]=3/5[limx-0 (sin3x/3x)]/[limx-0 (sin5x/5x)]=3/5*1/2=3/5希望帮你解决了本题.