• hansolo@lemmy.today
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      7 days ago

      …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
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        7 days ago

        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.xyz
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          7 days ago

          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
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          7 days ago

          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
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      6 days ago

      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.today
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        7 days ago

        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
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          7 days ago

          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.

  • PeriodicallyPedantic@lemmy.ca
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    6 days ago

    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.

    • tetris11@feddit.uk
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      6 days ago

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

        • tetris11@feddit.uk
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          6 days ago

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

          • Machinist@lemmy.world
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            5 days ago

            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. 😁

  • throwawayacc0430@sh.itjust.works
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    7 days ago

    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]

  • Saarth@lemmy.world
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    6 days ago

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

  • Lovable Sidekick@lemmy.world
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    6 days ago

    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.

  • TheLeadenSea@sh.itjust.works
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    8 days ago

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

    • Snazz@lemmy.world
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      7 days ago

      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
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        7 days ago

        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
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        7 days ago

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

        • supernicepojo@lemmy.world
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          7 days ago

          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
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            6 days ago

            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
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    8 days ago

    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
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      7 days ago

      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.