已知sin(a+b)等于2/3,sin(a-b0 =1/5sin(a+b)/sin(a-b)=(sina*cosb+cosa*sinb)/(sina*cosb-cosa*sinb) 分式上下同除以cosa*cosb=(tana+tanb)/(tana-tanb) =(tana/tanb+1)/(tana/tanb-1)=(2/3)/(1/5) 所以tana/tanb=7/...