f(x)=cos^2x-sin^2x+2(根号3)sinxcosx+1=cos2x+(根号3)sin2x+1=2{(1/2)cos2x+[(根号3)/2]sin2x}+1=2sin(2x+派/6)+1,T=2派/2=派递增区间[K派-派/3,K派+派/6]2sin(2a+派/6)+1=2,2a+派/6=5派/6,a=派/3,
