• hihi24522@lemm.ee
    link
    fedilink
    arrow-up
    1
    ·
    13 days 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.

  • RandomVideos@programming.dev
    link
    fedilink
    arrow-up
    0
    ·
    edit-2
    13 days ago

    What kind of problem gives you the formula and all variable to replace? At this point, why not just write 5•10²•10=?

    • SaharaMaleikuhm@feddit.org
      link
      fedilink
      arrow-up
      1
      ·
      12 days 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.

      • andros_rex@lemmy.world
        link
        fedilink
        arrow-up
        1
        ·
        edit-2
        12 days 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.

        • nova_ad_vitum@lemmy.ca
          link
          fedilink
          arrow-up
          1
          ·
          12 days 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.

    • Oxysis/Oxy@lemmy.blahaj.zone
      link
      fedilink
      English
      arrow-up
      0
      arrow-down
      1
      ·
      13 days 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
        link
        fedilink
        English
        arrow-up
        1
        ·
        13 days 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)

  • Chris@lemmy.world
    link
    fedilink
    arrow-up
    0
    ·
    13 days 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

    • Wanderer@lemm.ee
      link
      fedilink
      arrow-up
      0
      ·
      13 days 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@lemmy.world
        link
        fedilink
        arrow-up
        1
        ·
        12 days 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@lemmy.world
    link
    fedilink
    English
    arrow-up
    0
    ·
    13 days 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.

    • ftbd@feddit.org
      link
      fedilink
      arrow-up
      0
      ·
      13 days ago

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

      • Lovable Sidekick@lemmy.world
        link
        fedilink
        English
        arrow-up
        0
        ·
        13 days 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
          link
          fedilink
          English
          arrow-up
          1
          ·
          12 days ago

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

        • bss03@infosec.pub
          link
          fedilink
          English
          arrow-up
          0
          ·
          13 days 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
            link
            fedilink
            arrow-up
            1
            ·
            11 days 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

    • Opisek@lemmy.world
      link
      fedilink
      arrow-up
      0
      ·
      13 days ago

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

      • Lovable Sidekick@lemmy.world
        link
        fedilink
        English
        arrow-up
        1
        ·
        12 days 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.