• lowleveldata@programming.dev
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    8 months ago

    That’s how you know math is OP when you can calculate volumes in parallel worlds where circles don’t even looks like circles

  • Lemvi@lemmy.sdf.org
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    8 months ago

    With π=5 maths break down completely. If π=5, then e^(5i) = -1, meaning -1 = cos(5) + i * sin(5), or -1 ≈ 0.284 - 0.959 i

    • Bob@feddit.nl
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      8 months ago

      I think you’re overthinking it. The first thing you’re told when you learn algebra is that a letter represents a number and you can say “let a equal (number), b equal (number)…” so you can let pi equal whatever you want for the purposes of one simple problem.

      • CaptSneeze@lemmy.world
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        8 months ago

        You’re talking about variables. But, pi isn’t a variable, it is a constant number. This would be more akin to saying “let 7 = 9”.

        • skulblaka@startrek.website
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          8 months ago

          Except pi isn’t a variable. It is a known value that we refer to as pi for convenience, and pi is a fundamental aspect of how a circle is. Saying “let pi equal 5” is all fine and well but is physically impossible, you will not be determining the volume of a cylinder if you let pi equal 5, because the ratio of a circle does not equal 5, it equals 3.14

  • gimpchrist @lemmy.world
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    8 months ago

    Nobody knows how to think like a dyscalculic at all haha… it’s just a little symbol thingy… it doesn’t have to be pi. Just like X is a little symbol thingy… the x is now just kind of a table right now… it’s just a little symbol thingy and it means five it’s not that difficult. Lmao

    • nyctre@lemmy.world
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      8 months ago

      Yes it does have to be pi because that’s the formula for the volume of a cylinder. If you take a simple, cylindrical glass or container and measure it and apply the formula with pi, you’ll see that you’ll get the correct volume of the container. If you just want your kids to calculate a random x that’s 5* 10 *10 *10 just tell them to do that, don’t give them a made up formula, it’s not that difficult.

      • petrol_sniff_king@lemmy.blahaj.zone
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        8 months ago

        Mathematically, no, it does not. We make up the definitions. If you wanted to see what the consequences of a, I don’t know, 5-dimensional universe with Pi set to 5.65 were, you can do that. These are scribbles on pages, there is literally nothing stopping you.

        Academically, what’s stopping you is whether these calculations are useful. The only problem I see here is that it’s kind of misleading to imply to someone that Pi is something it conventionally isn’t. But even then, I think I’d respect the mathematician who could recognize Pi as a symbolic name for, usually, one particular transcendental constant a little bit more than one who refused to even entertain the idea. Like, imagination is important to mathematics, too.

        And to be clear, “let Pi = 3.14” is also incorrect. It is closer than 5, but it is still infinitely wrong.

        [edit] And also, I was imagining this question was for a younger audience. Reading it again, I’m not going to pretend I know what’s going on up there.

    • benignintervention@lemmy.world
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      8 months ago

      If you really wanted to be through you’d start at a point, integrate out along dr for a line, then integrate in a circle through dtheta to derive the area before doing the rest

  • Iron Lynx@lemmy.world
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    8 months ago

    To be Devil’s Advocate:
    Given that the rest written in Comic Sans, it may be an early elementary school exercise, aimed at teaching kids to do multiplications. In this case, it’s tolerable and/or defensible to find a simplification for pi.

    That said, making pi equal to 3 would have been more accurate for that…

    • ColeSloth@discuss.tchncs.de
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      8 months ago

      That’s a dumb way of teaching and you are a dumb devils advocate for saying it. Go to H E double hockey sticks.

      • Papergeist@lemmy.world
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        8 months ago

        Even in engineering it is common to just round pi to 3 and quickly estimate whatever it is your doing.

        • maniclucky@lemmy.world
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          8 months ago

          Excuse me what? I’ve been an engineer for a decade and have never met anyone that would do that. We have calculators.

            • Jimbo@yiffit.net
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              8 months ago

              We all have phones with calculators, don’t really need to do napkin math anymore

              • assassin_aragorn@lemmy.world
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                8 months ago

                Depends on the level of precision you need. If I want the volume in a 500 foot long, 3 inch pipe to roughly estimate how much supply I need to order, I wouldn’t need a calculator. It would very roughly be 90-95 ft3. (Divide 500 by 4 two times and multiple by 3)

                Then I would spend 5 minutes double checking myself haha.

            • maniclucky@lemmy.world
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              8 months ago

              I suppose. I’m still internally outraged and haven’t run into such a situation before, but I accept this.

                • maniclucky@lemmy.world
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                  8 months ago

                  That makes sense. I feel like if you’re at the point where pi is meaningfully involved, you should probably do your math.

        • PM_Your_Nudes_Please@lemmy.world
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          8 months ago

          In astronomy, pi=1 or 10, depending on whether you’re trying to over or under estimate something. Because when you’re trying to estimate distances measured in millions of light years, the difference between 3 and 10 is just one or two orders of magnitude on a small number. It’s pretty common for astronomers to do napkin math by rounding every single number to the nearest zero. 91k becomes 100k for instance. Because the napkin math estimations are just trying to gauge whether some celestial event or object is a thousand light years away, ten thousand, a hundred thousand, etc… And pi becomes 10, because that’s the nearest round number.

          • LazerFX@sh.itjust.works
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            8 months ago

            Fermi Estimation. Where you’re dealing with something so big, you’re just interested in the magnitude.

    • Duamerthrax@lemmy.world
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      8 months ago

      Unless the kid is even slightly above average and finds the idea that pi equaling 5 confusing.

      • NucleusAdumbens@lemmy.world
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        8 months ago

        …if they’re above average, I think they’ll figure out the explicitly defined variable. I think the instructor is trying to make sure this problem doesn’t require a calculator and figured defining pi as 5 makes it clear that you can treat it as a whole number. 3 would be more accurate and just as easy, but meh idk that this is that great of a blunder.

        • Duamerthrax@lemmy.world
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          8 months ago

          You can be a smart kid and not realize that adults are lying.

          I remember the Peas and the Punnett Square. Sure, mendelian genetics explains pea plant colors, but doesn’t explain dog fur colors. Just providing a footnote that more completed genetics exists would have been nice.

    • bluewing@lemm.ee
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      8 months ago

      Or it’s from an ME. They seldom can remember the rounded value of Pi, but they’re pretty sure it’s somewhere between 3 and 4. But you probably should use 5 just to be safe…

  • RegalPotoo@lemmy.world
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    8 months ago

    Idk, if you want to test people on how they understand formulae and order of operations without letting them just punch it into a calculator. The actual math isn’t hard, but if you don’t get substituting values into an equation then it’s not trivial

        • Serinus@lemmy.world
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          8 months ago

          Your life is easier and better if you can do this kind of simple math in your head.

          • Norgur@fedia.io
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            8 months ago

            Oh don’t you try to sell me on the “you won’t always have a calculator in your pocket” thing. I have fucking Excel in my pocket.

            • notabot@lemm.ee
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              8 months ago

              It’s not just about haveing a calculator, it’s also that it’s faster and more convenient if you can do simple sums like this in your head. It also means you can sanity check the numbers your calculator gives you to make sure you didn’t make a mistake entering the sum.

              To your point below about products having their unit cost displayed, more than once I’ve seen that just be wrong, so I wouldn’t rely on it. Make sure you can check it in your head.

            • Serinus@lemmy.world
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              8 months ago

              Who really wants to use Excel to figure out if the 24-pack of Coca-Cola or the 3 12 packs is a better deal?

              • Norgur@fedia.io
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                8 months ago

                I don’t need to, there’s a legal requirement to print prices per liter or kg on every price tag here.

                • HopFlop@discuss.tchncs.de
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                  8 months ago

                  But if you want to buy only half a kg, you don’t know how much it costs (if you dont know basic maths)- because it only lists the price for a full kg. Do you start pulling out your Excel for that?