• PeriodicallyPedantic@lemmy.ca
    20·
    2 天前

    I’m not a math major, but I always considered it that a square is a special case of rectangle, a rectangle is a special case of parallelogram, and a parallelogram a special case of a quadrilateral, a quadrilateral a special case of a simple polygon.

    This shape isn’t a polygon, so it cannot be a square.

  • Saarth@lemmy.world
    3·
    2 天前

    Don’t the internal angles need to be 90°? Two of those right angles aren’t right angles on the inside.

    • hansolo@lemmy.today
      27·
      3 天前

      …and a square has four interior 90 degree angles.

      …and based on the infinite number of sides for a curved line aspect, the “90 degree” angles would all be +/- the limit as it approaches zero, so never truly 90 degrees but always an infinite fraction away.

      • Caveman@lemmy.world
        4·
        3 天前

        Yeah, we gonna need more rigor on this one.

        “A square is a shape made up of four equally long lines a, b, c, d where a is perpendicular to c and d and parallel to b. Each of these lines meet exactly two other lines at it’s ends.”

        I’m not a mathematician so there might an odd case somewhere in there. Maybe it has to be confined to a shared plane?

        • Sneezycat@sopuli.xyzEnglish
          2·
          3 天前

          Lines are infinitely long… do you mean line segments?

          Wikipedia has a good enough definition: “It has four straight sides of equal length and four equal angles.” Nice and simple.

        • hansolo@lemmy.today
          1·
          3 天前

          So you’re saying this is the outline of a square in the astral plane? Because it sounds like you’re saying this is a square in the astral plane.

    • PeriodicallyPedantic@lemmy.ca
      7·
      2 天前

      Hey, that’s my job!

      Also I don’t think that’s technically the technical classification. I think that sidedness is an attribute that simply doesnt apply to curves.
      You can approximate curves with some number of sides, and the approximation gets more accurate as the number approaches infinity, but it doesn’t actually have the infinite sides.

      • YiddishMcSquidish@lemmy.todayEnglish
        5·
        3 天前

        If it is a projection, then there are more than two curved sides, which also begs credence to the interpretability of the angles they intersect.

        • danhab99@programming.dev
          41·
          3 天前

          Well angles between 3 points are always going to be angles. If your choose a different configuration of dimensional parameters you can effectively project a square from the 2D plane into this exact shape, then logically the angles would follow.

  • TheLeadenSea@sh.itjust.worksEnglish
    1622·
    4 天前

    Straight lines. Also two sets of parallel lines. This is one definition of a square, but not the common one.

    • Snazz@lemmy.world
      2·
      3 天前

      This shape could exist as a projection onto an upright cylinder, wrapping around the cylinder. The two straight edges go vertically along opposite sides of the cylinder. The curved lines wrap around the circumference. The lines are now straight and parallel on the net of the cylinder.

      But we can go further: Imagine taking this cylinder and extending it. Wrap it into a loop by connecting the top to the bottom so it forms a torus (doughnut) shape. This connects both sides of the shape, now all “interior” angles are on the inside of the square, and all “exterior” angles are on the outside. The inside and outside just happen to be the same side.

      • Zkuld@lemmy.world
        4·
        3 天前

        I would guess on a sphere these can be straight yes: The pole goes into the center of cicular thing and radius of the sphere needs to put the other arc on one latitude.

      • NateNate60@lemmy.world
        2·
        4 天前

        Euclid’s first postulate: Give two points, there exists exactly one straight line that includes both of them.

        • supernicepojo@lemmy.world
          4·
          3 天前

          This only applies in 2nd order real space. Euclidean geometry aside, I agree with at least one line could exist between two points

          • SparroHawc@lemmy.zip
            1·
            2 天前

            No, it’s still accurate - the straight line goes through the center of the Earth. Only in coordinate systems where ‘straight’ is defined as following the curvature of a surface are there infinite lines between the North and South Poles… and that would be non-Euclidean geometry.

  • halcyoncmdr@lemmy.world
    English
    1242·
    4 天前

    Someone never had to deal with mathematical proofs, only layman’s definitions.

    All properties of a parallelogram apply:

    • Opposite sides are parallel
    • Opposite sides are congruent
    • Opposite angles are congruent
    • Consecutive angles are supplementary
    • Diagonals bisect each other

    AND

    • All angles are congruent
    • All sides are congruent
    • Diagonals are congruent
    • Diagonals are perpendicular
    • Diagonals bisect opposite angles
    • Eatspancakes84@lemmy.world
      141·
      3 天前

      Of course, but such strict definitions only come about because smart people come up with examples like OP when you don’t add the full definition.

    • tetris11@feddit.ukEnglish
      2·
      2 天前

      uhhh, wait. Under what projection is OP’s “square” reduced to an actual square

        • tetris11@feddit.ukEnglish
          2·
          2 天前

          Im gonna need more than that as an explanation. Sandwiches too if you’re making some

          • Machinist@lemmy.worldEnglish
            2·
            1 天前

            Imagine you have a cookie cutter in that shape. Cut a cookie as thick as the chord of the largest arc.

            View the new vertical surface of the longest arc that is now a cylindrical section.

            Viola, square. 😁

  • burgersc12@mander.xyzEnglish
    7016·
    3 天前

    Does no one understand this is a joke, talking about parallel lines and mathematical proofs is pointless when its a fucking meme

    • dontbelievethis@sh.itjust.works
      36·
      3 天前

      It’s not pointless because you can laugh about a joke and then learn something about math.

      They don’t cancel each other out. They can be at the same place and still work on their own.

    • CyberEgg@discuss.tchncs.de
      225·
      3 天前

      We do understand it’s a meme and a joke. Just not a very good one, because one can easily poke holes into it.

      • daddycool@lemmy.world
        107·
        3 天前

        Just not a very good one, because one can easily poke holes into it.

        That’s not how jokes work.

          • daddycool@lemmy.world
            31·
            3 天前

            No, it depends on if you have humor. Yes, humor is individual, I know. But people without tend to over analyze and try to pick the joke apart, often missing the point.

            A joke doesn’t have to pass every technicality. You thinking it’s bad if it doesn’t, only applies to your humor (or lack there of).

            • CyberEgg@discuss.tchncs.de
              61·
              3 天前

              Ooh, watch out, the humor police is here! Everything the deem funny is humor and if you don’t find funny what they do you don’t even have humor! Wee-ooo wee-ooo!

                • CyberEgg@discuss.tchncs.de
                  2·
                  3 天前

                  And you cannot take criticism. Just saying.

                  (Also, I’m not picking apart the joke, I’m explaining why some people do.)

      • burgersc12@mander.xyzEnglish
        97·
        3 天前

        Its supposed to be absurd, taking it seriously makes the already bad joke even worse

        • CyberEgg@discuss.tchncs.de
          132·
          3 天前

          It’s not about taking it seriously. The meme wants to be a technically correct-meme, where a thing fulfills another things definition and thereby could be deemed the other thing - which creates the absurdity the meme lives off of. But in order for that kind of humour, there cannot be obvious holes in the logic of the joke and these obvious holes are very present in this meme.

          • MBM
            3·
            3 天前

            Any maths joke of this type will have obvious holes in it, that’s just how maths works

          • burgersc12@mander.xyzEnglish
            23·
            3 天前

            Well the text in the image of the “definition” of a square is clearly tailored to fit this joke, thats why the logic of what a square actually is doesn’t apply. Its like telling Diogenes that his chicken is not technically a human because it doesn’t have two hands and a nose.

            • CyberEgg@discuss.tchncs.de
              71·
              3 天前

              Diogenes plucked that chicken to point out Platon’s definition of a human (being a bipedal, featherless animal) being flawed. This meme leaves out parts of the definition to enforce a joke. Two different situations.

  • Lovable Sidekick@lemmy.worldEnglish
    1·
    2 天前

    Lines that intersect a circle like that aren’t “right angles” tho, they’re called “normal” to the circle - in other words pointing directly toward the center. A normal line is at right angles to a tangent line, but not to a curve.

    • MBM
      54·
      3 天前

      No it doesn’t. Right angles + equal length is a sufficient condition

        • MBM
          21·
          3 天前

          In that case, there’s no need to specify anything about the angles. Or, the characterisation the meme is playing with: a shape with four straight sides of equal length and right angles. Adding parallel to the meme’s version doesn’t help.

          I’m just tired of this thread. Not only do Lemmy users have this weird urge to show off their high school maths knowledge to dunk on a joke that obviously only works because OP played with the definition, but they’re not even correct. The /r/mathmemes thread was much better.

          • petrol_sniff_king@lemmy.blahaj.zone
            1·
            2 天前

            That weird urge is like 80% people feeling the need to correct OP’s grammar, like birds do when they hear the wrong birdsong, as if there were anything at stake here.

            Honestly, I wish people would play with definitions more. It’s fun. And, unironically, you would be a much better mathematician than most of the know-it-alls here.

  • throwawayacc0430@sh.itjust.worksEnglish
    16·
    3 天前

    Wrong. This is a definition of a [pizza] + [the extra peperoni from the other slices that got stuck to that slice because the cutting was imperfect]