f(x)=2(cosx)^2+√3sinxcosx+2=1+cos2x+√3/2*sin2x+2=cos2x+√3/2sin2x+3=√7/2*sin(2x+arctan2√3/3)+3,那么递减区间为[π/4-1/2*arctan2√3/3,3π/4-1/2*arctan2√3/3],对称中心为（-1/2*arctan2√3/3+kπ/2,0）f...