• Chris
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    602 months ago

    It’s probably trying to teach kids algebra without using decimals. But it does look messed up. Everyone knows at least 3.14, except kids I guess

      • HofmaimaierOP
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        222 months ago

        In Terry Pratchett’s wonderfully witty Discworld novel, Going Postal, the topic of pi comes up in a rather humorous and characteristically Pratchettian way.

        The newly appointed Postmaster General, Moist von Lipwig, encounters a rather eccentric inventor named Bloody Stupid Johnson. Bloody Stupid Johnson is known for his, well, stupidly brilliant inventions. One of these inventions is a new kind of postal sorting engine.

        When discussing the design of a wheel for this engine, Bloody Stupid Johnson proudly states that he designed it so that pi is exactly three.

        • dual_sport_dork 🐧🗡️
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          192 months ago

          This is in contrast with how pi is otherwise consistently expressed on the Disc, which is “three and a bit.”

          Notably, Bloody Stupid Johnson is so skilled/inept that he actually does make pi equal to three within the machine… somehow… which breaks reality in a small amount of space inside it.

          Apparently King David had this skill as well, since this is mentioned twice in the old testament:

          1 Kings 7:23: And he made a molten sea, ten cubits from the one brim to the other: it was round all about, and his height was five cubits: and a line of thirty cubits did compass it round about.

    • @Opisek@lemmy.world
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      62 months ago

      My dad told me a rhyme to memorize like 15 digits of pi before I knew what pi is at like eight years old I’m guestimating. I remember it ever since.

    • @Wanderer@lemm.ee
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      32 months ago

      I don’t understand. Aren’t fractions better than decimals for algerba?

      Like 22/7 is better than 3.14 when it comes to pi for example.

      We always got taught to do everything as fractions and then convert to units at the last possible moment to reduce errors in rounding.

      • Chris
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        22 months ago

        Kiddos would need to know how to divide for that though. I’m just trying to come up with a reason for it lol.

  • Lovable Sidekick
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    472 months ago

    Assigning a value of 5 to pi, although ludicrous IRL, doesn’t affect the problem. Plug the values into the equation and it will still give an answer that’s correct in context.

    • @Opisek@lemmy.world
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      132 months ago

      For the benefit of doubt, maybe the test is from an alternate dimension that doesn’t use euclidean space.

      • Lovable Sidekick
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        22 months ago

        Possible. I mean, electricity could actually be run by ghosts, but there’s no need for fanciful explanations when a mundane one is right there.

        • @bss03@infosec.pub
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          52 months ago

          Cause it’s just a (n-1)-dimensional ball extruded along the remaining axis, or do all 3d shapes exist on (nearly) all 3d metrics?

          • @Shardikprime@lemmy.world
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            32 months ago

            Mostly because the actual pi values can vary in between non/euclidean geometries. Within extremely strong gravitational fields, spacetime becomes highly non euclidean, affecting the C/d ratio of an actual circle, so I’d wager this would affect pi as well

      • Lovable Sidekick
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        62 months ago

        Technically no, because pi equals pi not 5. But you can approximate its value as 3 or 5 or whatever you want, knowing it’s not exact and that your result will only be an approximation. I mean you could also ask how long light takes to reach us from Alpha Centauri if the speed of light is 1000 mph. It’s not, but if you make that a condition of the problem you can do the calculation just fine.

        • @bss03@infosec.pub
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          22 months ago

          I think that reason would make it “Technically Yes”, since False (pi = 5) implies False (cylinders exist) is (vacuously) True (“absurd premise”).

    • @ftbd@feddit.org
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      82 months ago

      If the goal is to avoid calculations with decimal places, why not just leave Pi in the result?

  • @hihi24522@lemm.ee
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    352 months ago

    It’s clearly just saying that the surfaces on which the ends of the cylinder lie are metric spaces with distances defined using Chebyshev or Taxicab metrics based on pentagonal tilings of the parabolic plane so the ratio of a circle’s circumference to diameter is 5.

    Since it’s a cylinder we assume the vertical dimension is Euclidean and voila the math checks out geometrically.

    • Oxysis/Oxy
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      92 months ago

      There’s good reasons they engineers over calculate, because they know things break, that people don’t do regular maintenance and that people will over stress the object. So engineers have to account for things like this when designing an object or a device so they don’t fail prematurely.

      • @explodicle@sh.itjust.works
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        172 months ago

        Engineer here, I always just use pi and a “safety factor” multiplier. Extra material is expensive, and I want the cheapest part (like a screw) to fail first. We don’t just oversimplify pi because half the time it’ll make your design weaker.

        (If I just got whooshed I apologize)

        • @RubberElectrons@lemmy.world
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          2 months ago

          100%, also how would I indicate to colleagues or successors when I used what value for pi? Clear diving is a thing for me.

          Safety factors are both more explicit and self-documenting up to a certain point.

      • @PeriodicallyPedantic@lemmy.ca
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        32 months ago

        I’m familiar

        It’s funny because engineers are known for making simplifications like this, not because the simplification is problematic

        • @nova_ad_vitum@lemmy.ca
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          82 months ago

          It makes it easy to do the math in your head without a calculator. But still , just tossing out pi=5 is not the way to go about creating these problems.

        • ...m...
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          52 months ago

          …fractal circumferences can be whatever length you want for any given mean radius…

      • @andros_rex@lemmy.world
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        2 months ago

        Even then, I would want them to leave π in the problem itself. That would be much better for this exercise - teaching that you report “exact” values with π still in them.

        Eg, if I rewrote this problem, I would expect an answer of 1000π.

    • @SaharaMaleikuhm@feddit.org
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      82 months ago

      Cause reading comprehension is part of the test. Lots of kids will be able to solve that equation, but there’s a bunch who can’t understand it if it’s presented this way.
      Honestly here they should have done “round pi to two decimal places” or smth.

    • kamen
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      152 months ago

      Even if so, the other factors are both 10. How hard can it be…

    • @syreus@lemmy.world
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      32 months ago

      I didn’t get to use a calculator IN CLASS until late in my bachelor studies — forget about using them for tests. In a world with Chatgpt we need to teach in a more sterile environment or standards are going to swing into the ditch. My friend who is a grade school teacher has told me some stories that would make your ears bleed.