• 若tan(α+π4)=34,则tan2α的值是 .试题及答案-填空题-云返教育

    • 试题详情

      若tan(α+
      π
      4
      )=
      3
      4
      ,则tan2α的值是         

      试题解答


      -
      7
      24

      解:∵tan(α+
      π
      4
      )=
      3
      4

      tanα+1
      1-tanα
      =
      3
      4

      ∴tanα=-
      1
      7

      ∴tan2α=
      2tanα
      1-tan2α
      =
      -
      2
      7
      1-
      1
      49
      =-
      7
      24

      故答案为:-
      7
      24
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