(1).y=sin2x+cos2x=√2sin(2x+π/4)
当x=kπ+π/8时,ymax=√2,周期T=2π/2=π
(2).y=sinx+√2cosx=√3sin(x+φ)
最大值为√3,周期T=2π/1=2π
(3).y=sinxcosx=1/2sin2x
当x=kπ+π/4时,yamx=1/2