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The 9 dot puzzle.

  1. Feb 11, 2009 #1
    This ones a classic and it doesn't seem it's come up before.

    But draw 9 dots in 3 rows and columns that are equidistant, now join them up with not more than 4 straight lines.

    If you already know it be sure not to give the game away. Just a simple problem I thought might pass a few moments to those who haven't seen it before.
     
  2. jcsd
  3. Feb 11, 2009 #2
    i'm not sure i understand the question, because i've already thought of 5 answers
     
  4. Feb 11, 2009 #3

    Hurkyl

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    He forgot to say that the line (segments) have to be drawn contiguously; each line segment begins where the previous one ends.
     
  5. Feb 11, 2009 #4
    A solution...
     
    Last edited: Feb 11, 2009
  6. Feb 11, 2009 #5
    I decided to remove the figure cause there is no "spoiler mode" for figures...

    For the points below

    ................
    ..1...2...3...
    ................
    ..4...5...6...
    ................
    ..7...8...9...
    ................

    use these lines:

    [3->7] [7->0] [0->10] [10->8]

    ....................
    ..0.................
    ....................
    ..1...2...3.......
    ....................
    ..4...5...6.......
    ....................
    ..7...8...9...10
    ....................
    :smile:
     
    Last edited: Feb 11, 2009
  7. Feb 11, 2009 #6

    DaveC426913

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    This is the classic think-outside-the-box puzzle.
     
  8. Feb 11, 2009 #7
    ah, yes, i remember it now. even though i remembered the basic strategy, it still took a few tries in my head to arrive at the result.
     
  9. Feb 12, 2009 #8
    Oh yes apologies. It must be a continuous line, ie you're not allowed to lift your pen from the paper.

    Well done those who got it, yeah it is a classic but it stumps so many people I rather like it. It's one of those puzzles were people impose rules on themselves.
     
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