How Do You Connect 9 Dots with 4 Lines?

[Rahmuss]

This is one I learned in grade school.

Connect the 9 dots with only 4 straight lines and without lifting your pencil / mouse.

http://img12.echo.cx/my.php?image=9dots4bl.png

 

[Jimmy Snyder]

I remember it from grade school too. A real example of thinking outside the box.

 

[JamesU]

Funny, we were doing this very problem in school today

 

[brewnog]

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.

 

[cerberus]

I did this in psychology class last year, outside the box is right.

 

[whozum]

This one is pretty cool.

 

[lueffy]

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...

 

[ArielGenesis]

is there is any out side the box puzzle, it is really interesting

 

[Rahmuss]

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.

Anyone who has not learned it previously have an answer for it?

 

[TenaliRaman]

Hmm, how abt this?

-- AI

 

[Rahmuss]

That's the one.

 

[matthyaouw]

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.

 

[Jimmy Snyder]

click on the link and then click on log off. Then the image will appear.

 

[ArielGenesis]

wow, that's a real nice bug

 

[gonpost]

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...

 

[Hurkyl]

I wonder if the hints helped.

 

[NateTG]

Well, you can do fun things like folding/bending the paper to get even fewer lines.

 

[Alkatran]

The dots aren't points (infinitely small) so you can do it in three if you make the line segments very very long.

 

[DrKareem]

Oh man, for some reason i thought you can't cross the line that you already drew. Otherwise i would have solved it.

 

[Zygotic Embryo]

i can't get it

 

[Zygotic Embryo]

Nvm i got it. Finally.

 

[Dr. Robotnik]

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

 

[dipinsingh]

I think this puzzle has already been solved.
Can anyone do it with three straight lines without lifting the pen or pencil?

 

[davee123]

I think this puzzle has already been solved.
Can anyone do it with three straight lines without lifting the pen or pencil?

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.

DaveE

 

[dipinsingh]

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.

DaveE

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.

 

[mabs239]

Funny, we were doing this very problem in school today

Do you always busy doing it? If not, this link might be interesting:

http://www.damninteresting.com/?p=417"

 

[maze]

http://img213.imageshack.us/img213/1821/3linessmallwc9.png