f(x)=2cosx(sinx-cosx)+1
=2sinxcosx-2(cosx)^2+1
=sin2x-cos2x
=sin2x-sin(π/2-2x)
=2cosπ/4sin(2x-π/4)
=√2sin(2x-π/4)
所以最小正周期=2π/2=π
f(x)=2cosx(sinx-cosx)+1
=2sinxcosx-2(cosx)^2+1
=sin2x-cos2x
=sin2x-sin(π/2-2x)
=2cosπ/4sin(2x-π/4)
=√2sin(2x-π/4)
所以最小正周期=2π/2=π