• 已知,则的值为试题及答案-单选题-云返教育

    • 试题详情

      已知,则的值为         

      试题解答


      A

      =
      =
      =2sin2α=2(1-cos2α)
      =2(1-
      )=2(1-
      =2(1-
      )=
      故选A
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