• Re: Divide a shape into four equal parts

    From ilan_no_spew@ilan_no_spew@hotmail.com (IlanMayer) to rec.puzzles on Fri Jul 4 16:03:54 2025
    From Newsgroup: rec.puzzles

    On Fri, 4 Jul 2025 15:47:04 +0000, Carl G. wrote:

    On 7/1/2025 7:36 PM, IlanMayer wrote:
    On Tue, 1 Jul 2025 19:01:29 +0000, Richard Tobin wrote:

    A well-known puzzle is to divide an L-shape - a square with one square
    quarter removed - into four identical pieces.

    But what about a square where the quarter removed is an isosceles
    right-angled triangle with one of the sides as its hypotenuse?

    This problem was set in Peter Parley's Annual, 1877, but I fear that
    they are no longer available to provide the answer:

    https://i.ebayimg.com/images/g/BZUAAOSwPqVlS8OY/s-l1600.jpg
    or
    https://web.archive.org/web/20250701185837/https://i.ebayimg.com/images/g/BZUAAOSwPqVlS8OY/s-l1600.jpg

    -- Richard

    SPOILER <snipped>

    Ilan,

    I had considered writing a computer program to solve this puzzle and
    similar puzzles. Did you write a program to solve this puzzle? If so,
    what algorithm did it use?

    No program; I solved this manually by dividing the shape into right
    triangles and grouping them together.

    --
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  • From David Entwistle@qnivq.ragjvfgyr@ogvagrearg.pbz to rec.puzzles on Sat Jul 5 07:47:26 2025
    From Newsgroup: rec.puzzles

    On Tue, 1 Jul 2025 19:01:29 -0000 (UTC), Richard Tobin wrote:

    A well-known puzzle is to divide an L-shape - a square with one square quarter removed - into four identical pieces.

    I haven't attempted your original question yet, but for anyone who has.
    Henry Ernest Dudeney had a variation of that first puzzle in "Amusements
    in Mathematics". He also has a variation on the puzzle with the square,
    with a triangle removed. More on that later. Here's the first variation...

    180. THE FOUR SONS

    Readers will recognize the diagram as a familiar friend of their youth. A
    man possessed a square shaped-estate. He bequeathed to his widow the
    quarter of it that is shaded off. The remainder was to be divided
    equitably amongst his four sons, so that each should receive land of
    exactly the same area and exactly similar in shape. We are shown how this
    was done. But the remainder of the story is not so generally known. In the centre of the estate was a well, indicated by the dark spot, and benjamin, Charles and David complained that the division was not "equitable," since Alfred had access to this well, while they could not reach it without trespassing on somebody else's land.The puzzle is to show how the estate
    is to be apportioned so that each son shall have land of the same shape
    and area, and each have access to the well without going off his own land.

    The accompanying image is available here:

    http://www.puzzles.50webs.org/pics/q180.png

    Most of the puzzles from Dudeney's book are available here:

    http://www.puzzles.50webs.org/index.html
    --
    David Entwistle
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  • From David Entwistle@qnivq.ragjvfgyr@ogvagrearg.pbz to rec.puzzles on Sun Jul 6 07:36:08 2025
    From Newsgroup: rec.puzzles

    On Wed, 2 Jul 2025 02:36:29 +0000, IlanMayer wrote:

    A well-known puzzle is to divide an L-shape - a square with one square
    quarter removed - into four identical pieces.

    But what about a square where the quarter removed is an isosceles
    right-angled triangle with one of the sides as its hypotenuse?

    This problem was set in Peter Parley's Annual, 1877, but I fear that
    they are no longer available to provide the answer:

    https://i.ebayimg.com/images/g/BZUAAOSwPqVlS8OY/s-l1600.jpg or
    https://web.archive.org/web/20250701185837/https://i.ebayimg.com/ images/g/BZUAAOSwPqVlS8OY/s-l1600.jpg

    -- Richard

    SPOILER

    Hi Ilyan,

    I failed to find a solution after an hour or so of looking (shuffling bits
    of paper), so was fascinated to see a solution.

    Are we sure those shapes are identical? Two look the same, one looks to be
    a reflection of the first two, and the third looks to be a different
    shape. They all have the same area, but I don't think you would describe
    them as the same shape.

    Apologies if I have this wrong, which I may well do.

    I think the problem is very much related to the second of Dudeney's
    problems, which I'll post shortly.
    --
    David Entwistle
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