f(x)=-4(cosx)^2+4√3*sinxcosx+5=-2[2(cosx)^2-1]+2√3*2sinxcosx+3=-2cos2x+2√3sin2x+3=-4(cos2xcosπ/3-sin2xsinπ/3)+3=-4cos(2x+π/3)+3.当cos(2x+π/3)=1,即 2x+π/3=2kπ ,x=kπ-π/6时,f(x)有最小值：-1.所...