17 replies to this topic

[rookie1ja]

Open polygon - Back to the Cool Math Games
Connect all 9 dots with 4 straight lines without lifting the pencil off the paper, and without going over the same line twice.



This old topic is locked since it was answered many times. You can check solution in the Spoiler below.
Pls visit New Puzzles section to see always fresh brain teasers.

Spoiler for Solution

Open Polygon - solution

[imtcb]

E

[mannu]

|
| /
* * *
| /
* * *
| /
*__*__ *_


this way

[mannu]

I apologise if thats not clear ...thts bcoz i dont know how to draw it in this editor...

But to describe it in words, draw a line joining the pts at the left side of the array of points and then another one joining the last row......now extend the two lines a little. Now draw another line from here thru the 2nd and sixth point... The last one id drawn as a diagonal to the square formed by the array of dots...

[Fysh]

You didn't meet the requirements of the solution with an open polygon. There is a closed polygon and a line, but that doesn't make an open one.

[simplyhumble]

x - l

[coldone]

i did it this way
4....5
-*---*..* 2
..... /|
.*...*...*
../....|
.*...*...*
1.......| 3
1-2-3-4-5
just dot(.)= space( )

[bigskybuuck]

how about three vertical lines and one horizontal

[beck]

123
456
789

6-2-4-7-9

edit: bah, jumped ahead of myself. didn't use all 9

Edited by beck, 30 January 2008 - 12:17 AM.

[stevo1904]

1000020000300000
00 0
0 0 0
0 0 0
0 0 0
4 5 6
0 0 0
0 0
0 0 0
0 0 0
7 8 9
0 0
0 0
0 0
0 0
0

sorry about the diagram,did the best I could! anyway start at 1 draw a line thru 2 and 3 going past 3 far enough
to draw a 45 degree line thru 6 and eight extending past 8 to line up 7,4 and 1.draw a line thru 7,4,and 1.
now 45 deg. thru 1,5 and 9.
Had to do this for 5th grade math extra credit way back when,only you couldn't lift pencil from paper.