已知2Sinb=Sin(2a+b),求Tan(a+b)比Tanb的值

已知2Sinb=Sin(2a+b),求Tan(a+b)比Tanb的值

2sinb=sin(2a+b)
令sinb=1/2
sin(2a+b)=1
b=30,2a+b=90
a=30
tan(a+b)/tanb=tan60/tan30=3