f(x)=2cos²x-2√3sinxcosx
=cos2x+√3sin2x
=2(1/2cos2x+√3/2sin2x)
=2cos(2x-π/3)
(1)向右平移π/6得m(x)=2cos(2x)[平移变换]
(2)垂直缩小1/2倍得n(x)=cos2x　[振幅变换]
(3)水平缩小1/2倍得g(x)=cosx　[周期变换]
f(x)=2sin（2x+πf(x)=2sin[π/2-(2x+π/6）]=2cos[-2x+π/3]=2cos(2x-π/3)
方法同上