(I)f(x)=sin2x+cos2x=
2 (
2
2 sin2x+
2
2 cos2x) =
2 sin(2x+
π
4 ) ,
∴ T=
2π
2 =π .
(II)由 -
π
2 +2kπ≤2x+
π
4 ≤
π
2 +2kπ ,解得 -
3π
8 +kπ≤x≤
π
8 +kπ (k∈Z).
∴函数f(x)的单调递增区间是 [-
3π
8 +kπ,kπ+
π
8 ] (k∈Z).
(I)f(x)=sin2x+cos2x=
2 (
2
2 sin2x+
2
2 cos2x) =
2 sin(2x+
π
4 ) ,
∴ T=
2π
2 =π .
(II)由 -
π
2 +2kπ≤2x+
π
4 ≤
π
2 +2kπ ,解得 -
3π
8 +kπ≤x≤
π
8 +kπ (k∈Z).
∴函数f(x)的单调递增区间是 [-
3π
8 +kπ,kπ+
π
8 ] (k∈Z).