f(x)=2sinxcosx-2sin^2x+1
=sin2x+cos2x
=√2sin(2x+π/4)
（1） 最小正周期T=2π/2=π
(2) 单增区间2x+π/4∈[2kπ-π/2,2kπ+π/2]
x∈[kπ-3π/8,kπ+π/8 k∈Z