f(x) = sin^2(x+π/6)+cos2x = (1 - cos(2x+π/3))/2 + cos2x = 3/4*cos2x+3^0.5/4sin2x+1/2 = 3^0.5/2cos(2x-π/6)+1/2因为cos(2x-π/6)的最小正周期是π,所以经过平移和拉伸后,根据其图像可得其周期为2π
先用半角公式sin^2(x)=(1-cos2x)/2降幂 化简为[1-cos(2x+π/3)]/2+cos2x 该式与函数f(x)=cos2x周期相同为π