吗了隔壁
幼苗
共回答了19个问题采纳率:94.7% 举报
f(x)=cos2x.cos(π/3-2x)
=cons2x(0.5cos2x+√3/2sin2x)
=1/2(cos2x)^2+√3/2sin2xcos2x
=1/4(cos4x+√3sin4x)+1/4
=1/2cos(4x-π/3)+1/4,
所以单调减区间是(π/12+kπ/2,π/3+kπ/2).
y=sin(2x+π/6)+cos(2x+π/3)
=cos2x+√3sin2x
=2cos(2x-π/3)
所最小正周期T=π,值域为(-2,2)
1年前
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