y=sin2x+cos2x在x∈(0,π/2)上单调增区间是?..y=sin2x+cos2x在x∈(0,π/2)上单调增区间是?A.(π/4) B.(0,π/8) C.(0,π/4)D.(3π/8,π/2)

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y=sin2x+cos2x在x∈(0,π/2)上单调增区间是?..y=sin2x+cos2x在x∈(0,π/2)上单调增区间是?A.(π/4) B.(0,π/8) C.(0,π/4)D.(3π/8,π/2)
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y=sin2x+cos2x在x∈(0,π/2)上单调增区间是?..y=sin2x+cos2x在x∈(0,π/2)上单调增区间是?A.(π/4) B.(0,π/8) C.(0,π/4)D.(3π/8,π/2)
y=sin2x+cos2x在x∈(0,π/2)上单调增区间是?..
y=sin2x+cos2x在x∈(0,π/2)上单调增区间是?
A.(π/4) B.(0,π/8) C.(0,π/4)D.(3π/8,π/2)

y=sin2x+cos2x在x∈(0,π/2)上单调增区间是?..y=sin2x+cos2x在x∈(0,π/2)上单调增区间是?A.(π/4) B.(0,π/8) C.(0,π/4)D.(3π/8,π/2)
有配角公式asinx+bcosx=√(a²+b²)sin(x+φ) 其中sinφ=b/a,
此题y=√2sin(2x+π/4),
1≤sin(2x+π/4)≤1
2kπ-π/2≤2x+π/4≤2kπ+π/2 (k∈Z)时,即kπ-3π/8≤x≤kπ+π/8 (k∈Z),函数单调递增.
2kπ+π/2≤2x+π/4≤2kπ+3π/2 (k∈Z)时,即kπ+π/8≤x≤kπ+5π/8 (k∈Z),函数单调递减.
递增中,k=0时,x属于[-3π/8,π/8]选B