Math Trick Question

Date: 02/02/2005 at 00:01:55
From: Hastings
Subject: I am a teacher and my students have asked me this.

How do I draw a square using only 3 lines?

Date: 02/02/2005 at 12:48:36
From: Doctor Douglas
Subject: Re: I am a teacher and my students have asked me this.

Hi Hastings.

Surely it's a trick question, perhaps involving folding the paper or 
turning it underneath the pencil, etc.

Or, here's another twist:

      A
     /|          DA, AB, and BC are the three lines.
    / |          and "4", of course, is the square:  4 = 2*2.
   /  |
  B---+-C        The same idea works for "1" as well.
      |
      D

- Doctor Douglas, The Math Forum
  http://mathforum.org/dr.math/