f(x)=sinx/(cosx-2)f'(x)=[cosx(cosx-2)-sinx(-sinx)]/(cosx-2)^2=[1-2cosx]/(cosx-2)^2=0,得极值点cosx=1/2,x1=2kπ+π/3,x2=2kπ-π/3f(x1)= √3/2(1/2-2)= -√3/3为极小值,也是最小值f(x2)=(- √3/2)/(1/2-2)= √...