cx2210
春芽
共回答了23个问题采纳率:78.3% 举报
a+b=(sinx+cosx,1/2)
y=(a+b)*b=sinxcosx+cos^2x+3/4
=sin2x/2+cos^2x-1/2+1/2+3/4
=sin2x/2+cos2x/2+5/4
=根号2/2sin(2x+π/4)+5/4
最小正周期:2π/2=π
单调递增:
2x+π/4=-π/2+2kπ(k∈Z)
2x=-3π/4+2kπ
x=-3π/8+kπ
2x+π/4=π/2+2kπ(k∈Z)
2x=π/4+2kπ
x=π/8+kπ
[-3π/8+kπ,π/8+kπ](k∈Z)
1年前
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