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Nine Dots

  1. May 25, 2005 #1
  2. jcsd
  3. May 25, 2005 #2
    I remember it from grade school too. A real example of thinking outside the box.
  4. May 25, 2005 #3


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    Funny, we were doing this very problem in school today :tongue:
  5. May 25, 2005 #4


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    Very funny, I was talking about this one with friends at Uni today!

    As jimmy said, it's definitely one to think outside the box on.
  6. May 25, 2005 #5
    I did this in psychology class last year, outside the box is right.
  7. May 25, 2005 #6
    This one is pretty cool.
  8. May 25, 2005 #7
    Yea, i also learned this from the grad, i think you people and people in my country was quite different, but then this is the same thing we done then...........
  9. May 26, 2005 #8
    is there is any out side the box puzzle, it is really interesting
  10. May 27, 2005 #9
    LOL... that's so funny that so many people were recently doing this one, or had learned it the same way I did. That's great. Well it's a classic then. :biggrin:

    Anyone who has not learned it previously have an answer for it???
  11. May 27, 2005 #10
    Hmm, how abt this?

    -- AI

    Attached Files:

  12. May 27, 2005 #11
    That's the one. :smile:
  13. May 28, 2005 #12


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    I'm still puzzling over it, and the forum still refuses to let me view attachments in the brain teasers board. Can anyone describe the answer to me or post an off-site link?

    Edit- never mind, googled it.
    Last edited: May 28, 2005
  14. May 28, 2005 #13
    click on the link and then click on log off. Then the image will appear.
  15. May 28, 2005 #14
    wow, that's a real nice bug
  16. Jun 2, 2005 #15
    Wow, I think that's one of the few brainteasers I've gotten within seconds of looking at it... but it wasn't really thinking outside of the box, there were still four 2D lines...
  17. Jun 2, 2005 #16


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    I wonder if the hints helped. :smile:
  18. Jun 10, 2005 #17


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    Well, you can do fun things like folding/bending the paper to get even fewer lines.
  19. Jun 10, 2005 #18


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    The dots aren't points (infinitely small) so you can do it in three if you make the line segments very very long.
  20. Jun 12, 2005 #19
    Oh man, for some reason i thought you can't cross the line that you already drew. Otherwise i would have solved it.
  21. Jul 7, 2005 #20
    i cant get it
  22. Jul 7, 2005 #21
    Nvm i got it. Finally.
  23. Jul 7, 2005 #22
    To view attachments you just need to click on it, then when you get the "You need blah blah blah" press logout.

    Incase you don't feel like loging out then inn agian I upped TenaliRamans photo to imageshack(I hope that was okay, TenaliRamans ;).
    http://img272.imageshack.us/img272/4090/9dots4bl0er.gif [Broken]
    Last edited by a moderator: May 2, 2017
  24. Aug 27, 2008 #23
    I think this puzzle has already been solved.
    Can any one do it with three straight lines without lifting the pen or pencil?
  25. Aug 27, 2008 #24
    I think it should be pretty clear that it's not possible with 3, unless something like:

    - you have a REALLY thick pen
    - you can manipulate the paper (bend, fold, tear, etc)
    - you assume "straight" lines can be something else like "y=2" in polar coordinates
    - etc.

    Some playing around will demonstrate that you cannot connect more than 3 dots with a single straight line in this example. Hence, your first line can connect 3 dots, and each subsequent line can add as many as 2 additional dots to your connection. So 3 lines will allow you to connect 3+2+2=7 dots, and 4 lines will allow you to connect 3+2+2+2=9 dots.

  26. Aug 27, 2008 #25

    Please note that these are not points but circular dots which can be joined by three straight lines even without thick pen.
    Just start from top of first dot, cross from middle of second dot and touch bottom of third dot and extend up to some point such that when u can draw a straight line back joining top of last dot in middle line, centre of middle dot of middle line and then bottom of first dot of middle line.
    Similarly draw third line for bottom line dots.
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