Puzzle: how would you divide the land equally? (spoilers)

While I normally post math puzzles on Monday, I found another interesting puzzle so there is a bonus problem this week.

Here is the problem.

A father dies and wants to divide his land evenly amongst four sons. The plot of land has the following unusual shape:

How can you divide the land into four equal parts, using only straight lines?

Give it a try before reading the answer below.

SPOILER ALERT: don’t scroll until you are ready. Solution is just below

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I came across this puzzle when it was presented to gifted math students.

Several of the high school students them were able to come up with the following solution.

I feel like this is the type of solution one might come up with–it is symmetric and somehow “makes sense.”

One of the students had shown a lot of creativity in his work. He came up with the above solution, but he also submitted a second answer that definitely took me by surprise, as follows.

It is amazing to see how the shape can be divided into four parts using scaled down versions of itself. Well done if you came up with this answer on your own.

(I would love to see what would happen if you iterate the process: take each of the four small pieces and divide them again into four small pieces. I could not figure out a quick way to do this working manually–if someone figures it out I’d love to see the shape if there is an interesting fractal pattern to it.)

[Edit 9-16]: V Paul Smith has taken up the challenge and done a manual tessellation. Here is what it looks like. It’s absolutely beautiful (click on it to see the full image)



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  • http://vpsgraphics.com V Paul Smith Jr

    The second version is the one I came up with.

  • http://vpsgraphics.com V Paul Smith Jr

    I manually iterated this several times, enough to see where it’s going. I colored the repeated instance of each of the 4 original locations.
    http://goo.gl/EKYA5
    If somebody else can come up with an automated way that’ll take this further, go for it.

  • http://www.mindyourdecisions.com/blog/ Presh Talwalkar

    Thank you–this is absolutely beautiful! I am posting your picture at the end of the article just in case people forget to follow your link.

  • Jean-Philippe Burelle

    I believe these have been studied before under the name “rep-tiles” :
    http://mathworld.wolfram.com/Rep-Tile.html

    There are a few more examples there. I learnt about them in a chapter of “The Colossal Book of Mathematics” by Martin Gardner.

  • Jon Banks

    Here’s an ugly answer where one brother gets a very unfortunate shape of land. http://i.imgur.com/hW9DP.png

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