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问题: 三角函数

解答:

(1) 最小正周期 T=2π/2=π
  单调增区间:2x+π/4∈[2kπ-π/2,2kπ+π/2]
       ---> x∈[kπ-3π/8,kπ+π/8],k∈Z
(2) f(x)≥1--->sin(2x+π/4)≥-√2/2
      --->2x+π/4∈[2kπ-π/4,2kπ+5π/4]
       ---> x∈[kπ-π/4,kπ+π/2],k∈Z
(3) f(x) = √2sin(2x+π/4)+2
     = √2cos(2x+π/4-π/2)+2
     = √2cos[2(x-π/8)]+2
即:f(x)图像由cos2x图像向右平移π/8单位再向上平移2单位得到