• calcopiritus@lemmy.world
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    22 days ago

    This triangle is impossible.

    If the distance between B and C is 0, B and C are the same points. If that is the case, the distances between A and B and A and C must be the same.

    However, i ≠ 1.

    If you want it to be real (hehe) the triangle should be like this:

        C
        | \
    |i| |  \ 0
        |   \
        A---B
         |1|
    

    Drawing that on mobile was a pain.

    As the other guy said, you cannot have imaginary distances.

    Also, you can only use Pythagoras with triangles that have a 90° angle. Nothing in the meme says that there’s a 90° angle. As I see it, there are only 0° and 180° angles.

    Goodbye, I have to attend other memes to ruin.

  • manucode@infosec.pub
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    22 days ago

    1 • 1 + i • i = 1 + (-1) = 0 = 0 • 0

    Pythagoras holds, provided there’s a 90° angle at A.

      • Xerodin@lemm.ee
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        22 days ago

        When talking about AC power, some of the power consumed doesn’t actually produce real work. It gets used in the generation of magnetic fields and charges in inductors and capacitors.

        The power being used in an AC system can be simplified by using a right triangle. The x axis is the real power being used by resistive parts of the circuit (in kilowatts, KW). The y axis is reactive power, that is power being used to maintain magnetic fields and charges (in kilovolt-amperes reactive, KVAR). And the hypotenuse is the total power used by the circuit, or KVA (kilovolt-amperes).

        Literal side note: they’re all the same units, but the different sides of the triangle are named differently to differentiate in writing or conversation which side of the power triangle is being talked about. Also, AC generator ratings are given in KVA, so you need to know the total impedance of your loads you want to power and do a bit of trig to see if your generator can support your loads.

        The reactive component of AC power is denoted by complex numbers when converting from polar coordinates to Cartesian.

        Anyways, I almost deleted this because I figured your comment was a joke, but complex numbers and right triangles have real world applications. But power triangles are really just simplifications of circles. By that I mean phasors rotating in a complex plane, because AC power is a sine wave.

        • snooggums@lemmy.world
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          22 days ago

          By that I mean phasors rotating in a complex plane, because AC power is a sine wave.

          I read the entire thing as Air Conditioning and it made me think my tired ass had forgotten something important and then here comes like whiplash when it clicked that you were talking about Alternating Current.

          More coffee needed.

        • Suzune@ani.social
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          22 days ago

          Please be careful with two different things. Complex numbers have two components. Distances don’t. They are scalars. The length of the vector (0,1) is also 1. Just as a+bi will have the length sqrt(a^2 + b^2). You can also use polar coordinates for complex numbers. This way, you can see that i has length 1, which is the distance from 0.

          The triangle in the example above adds a vector and a scalar value. You can only add two vectors: (1,0) + (0,1) which results in (1,1) with the proper length. Or you can calculate the length/distance (absolute values) of the complex numbers directly.

      • Brainsploosh@lemmy.world
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        22 days ago

        They’re about as imaginary as numbers are in general.

        Complex numbers have real application in harmonics like electronics, acoustics, structural dynamics, damping, regulating systems, optronics, lasers, interferometry, etc.

        In all the above it’s used to express relative phase, depending on your need for precision you can see it as a time component. And time is definitely a direction.

        • Kogasa@programming.dev
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          21 days ago

          That’s not relevant to what they said, which is that distances can’t be imaginary. They’re correct. A metric takes nonnegative real values by definition

          • Brainsploosh@lemmy.world
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            21 days ago

            Why can’t a complex number be described in a Banach-Tarsky space?

            In such a case the difference between any two complex numbers would be a distance. And sure, formally a distance would need be a scalar, but for most practical use anyone would understand a vector as a distance with a direction.

    • Foofighter@discuss.tchncs.de
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      22 days ago

      But that’s not the definition of the absolut value, I.e. “distance” in complex numbers. That would be sqrt((1+i)(1-i)) = sqrt(2) Also the triangle inequality is also defined in complex numbers. This meme is advanced 4-4*2=0 Works only if you’re doing it wrong.

  • xylogx@lemmy.world
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    22 days ago

    In the complex plane each of these vectors have magnitude 1 and the distance between them is square root of two as you would expect. In the real plane the imaginary part has a magnitude of zero and this is not a triangle but a line. No laws are broken here.

  • i_love_FFT@jlai.lu
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    20 days ago

    I kept seeing this pop up recently, and I finally understand it: it’s an introductory problem in Lorentzian general relativity.

    AB is a space-like line, while AC is a time-like line. Typically, we would write AC as having distance of 1, but with a metric such that squaring it would produce a negative result. However it’s similar to multiplying i to the value.

    BC has a distance of 0, but a better way of naming this line would be that it has a null interval, meaning that light would travel following this line and experience no distance nor time going by.

    I’m sure PBS Spacetime would explain all of this better than me. I just woke up and can’t bother searching for the correct words on my phone.

  • technocrit@lemmy.dbzer0.com
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    21 days ago

    Maybe the problem is constructing a metric that makes this diagram true. Something like d(x,y) = | |x| - |y| | might work but I’m too lazy to check triangle inequality.

    • stevedice@sh.itjust.works
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      20 days ago

      Triangle inequality for your metric follows directly from the triangle inequality for the Euclidean metric. However, you don’t need a metric for the Pythagorean Theorem, you need an inner product and, by definition, an inner product doesn’t allow non-real values.

  • OrganicMustard@lemmy.world
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    22 days ago

    You can make something like this properly by defining a different metric. For example with metric dl2 = dx2 - dy2 the vector (1, 1) has length 0, so you can make a “triangle” with sides of lengths 1, -1 and 0.

    • Kogasa@programming.dev
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      21 days ago

      That’s not a metric. In any metric, distances are positive between distinct points and 0 between equal points

      • OrganicMustard@lemmy.world
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        20 days ago

        It depends which metric definition are you using. The one I wrote is a pseudo-Riemannian metric that is not positive defined.

        Normally physicists use that generalized metric definition because spacetime in most cases has a metric signature of (-1, 1, 1, 1). Points with zero distance are not necessarily the same point, they just are in the same null geodesic.

        • Kogasa@programming.dev
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          20 days ago

          You’re talking about a metric tensor on a pseudo-Riemannian manifold, I’m talking about a metric space. A metric in the sense of a metric space takes nonnegative real values. If you relax the condition that distinct points have nonzero distance, it’s a pseudometric.

  • deikoepfiges_dreirad@lemmy.zip
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    21 days ago

    funny Interpretation: in the complex plane, the imaginary axis is orthogonal to the real axis. so instead of the edge marked with i (AC), imagine an edge of length 1 orthogonal to that edge. It would be identical to AB, so AC CB is 0.