tana=1/3,tanb=－2,则tan(a-b)=?
问题描述：
tana=1/3,tanb=－2,则tan(a-b)=?
答
tan(a-b)=(tana-tanb)/(1+tana*tanb)
=(1/3-(-2))/(1+1/3*(-2))
=7/3*3
=7