已知sina=msin(a+2b),m不等于1,求证:tg(a+b)=(1+m)/(1-m)*tgb.

因为,a=(a+b)-b,a+2b=(a+b)+b
所以,sin(a+b-b)=msin(a+b+b)
sin(a+b)*cosb-sinb*cos(a+b)=msin(a+b)*cosb+msinb*cos(a+b)
(1-m)sin(a+b)*cosb=(1+m)cos(a+b)sinb
所以,tan(a+b)=(1+m)/(1-m)tan