-1

enter image description here

Using 4 straight lines connect these 9 stars together without lifting your pen from the surface. The end of each line must be start of the next line.

Tryth
  • 13,960
  • 5
  • 39
  • 81
Artmis Shams
  • 73
  • 1
  • 5
  • 5
    This is a fairly standard puzzle, so lots of people will probably already know the answer. If I may make a suggestion - if you do already know at a glance, don't answer, let those who haven't seen it have a proper go at it. – Glen O May 03 '15 at 06:34
  • 2
    And to those who haven't seen this puzzle before, I just thought I'd say that you have to think outside the box to solve it. – Glen O May 03 '15 at 06:35
  • I feel like I've seen this on this site before, but can't find it. – Spencerkatty May 03 '15 at 16:05

3 Answers3

6

Is it valid that 2 of the corners are beyond the stars?

Here's my attempt!

Attempt

Dyrandz Famador
  • 811
  • 6
  • 13
5

I've never seen this one before, but here's what jumps out at me: enter image description here

Caleb
  • 1,146
  • 6
  • 13
  • I guess, but the "standard" puzzle that Glen references earlier in the comments basically assumes that the lines must pass through the centers of the stars/points/whatever. – Dennis Meng May 03 '15 at 07:45
  • 2
    Doesn't the second one not pass through the leftmost star? –  May 03 '15 at 08:06
  • @Reticality It does look that way, doesn't it? scratches head – Caleb May 03 '15 at 08:10
  • It just might work in Lobachevskian geometry. – Caleb May 03 '15 at 08:18
  • I love your first solution! The puzzle is about "thinking outside the box" (literally:)) and you took it to the next level with just 3 lines, nice! (The second solution is indeed faulty.) – egmont May 03 '15 at 10:27
3

Using the information from http://en.wikipedia.org/wiki/Parallel_(geometry)#Extension_to_non-Euclidean_geometry:

  1. parallel, if they do not intersect in the plane, but have a common limit point at infinity, or [...]

So, if we put this in a non-Euclidean plane, it can be done with one line:

One line

But, of course, this would take forever to draw (But it does pass through the centres of all stars)

I can also confirm it is impossible to do on a Euclidean plane without going outside the box with this Python script.

There are 84 different ways to do it with 5 lines inside the box, but that should be around 11 unique ones because most are reflected or rotated.