求y=2cos2x+2√3sinx•cosx-1的振幅，最小正周期，最大值及单调减区间．
y=2cos2x+2√3sinx•cosx-1=2[(1+cos2x)/2]+√3sin2x-1 =cos2x+√3sin2x=2[(1/2)cos2x+(√3/2)sin2x)=2[sin(π/6)cos2x+cos(π/6)•sin2x] =2sin(π/6+2x)． 振幅A=2，t=2π/2=π，ymax=2，ymin=-2 单调减区间[kπ+π/6，kπ+(2/3)π](k∈Z)
求y=2cos2x+2√3sinx•cosx-1的振幅，最小正周期，最大值及单调减区间．
y=2cos2x+2√3sinx•cosx-1=2[(1+cos2x)/2]+√3sin2x-1 =cos2x+√3sin2x=2[(1/2)cos2x+(√3/2)sin2x)=2[sin(π/6)cos2x+cos(π/6)•sin2x] =2sin(π/6+2x)． 振幅A=2，t=2π/2=π，ymax=2，ymin=-2 单调减区间[kπ+π/6，kπ+(2/3)π](k∈Z)
