3sinx=cosx-1,则tanx/2的值为

3sinx=cosx-1
6sin(x/2)cos(x/2)=-2[sin(2/x)]^2
sin(x/2)[3cos(x/2)+sin(x/2)]=0
所以sin(x/2)=0,3cos(x/2)+sin(x/2)=0
因此tanx/2=0或-3