sin(2A+B)=sin(2A)cosB+cos(2A)sinB,sin(2A)=2tanA/(1+tanA^2)=1,cos(2A)=(1-tanA^2)/ (1+tanA^2)=0, 则由sin(2A)cosB+cos(2A)sinB=3sinB得tanB=1/3,所以tan(A+B)=（tanA+tanB)/(1- tanAtanB)=2