this post was submitted on 29 Nov 2024
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Science Memes

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[–] calcopiritus@lemmy.world 85 points 1 month ago (7 children)

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.

[–] thomasloven@lemmy.world 22 points 1 month ago (1 children)

Context matters. In geometry i is a perfectly cromulent name for a real valued variable.

[–] Clinicallydepressedpoochie@lemmy.world 4 points 1 month ago (1 children)

Oh shit, he used the word cromulent. Every one copy off this guy.

[–] stevedice@sh.itjust.works 2 points 1 month ago

That wouldn't be cromulent, would it?

[–] Dayroom7485@lemmy.world 12 points 1 month ago

Mad mobile drawing!!

[–] technocrit@lemmy.dbzer0.com 5 points 1 month ago* (last edited 1 month ago) (1 children)

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

Incorrect. There are complex valued metric spaces

And even if we assume real valued metrics, then i usually represents the unit vector (0,1) which has distance real 1.

[–] stevedice@sh.itjust.works 1 points 1 month ago (1 children)

That's NOT a metric. That's a measure. Two wholly different things.

[–] diaphanous@feddit.org 3 points 1 month ago (1 children)
[–] stevedice@sh.itjust.works 1 points 1 month ago

That's more related to a metric but it still can't be complex valued and it's still not a measure.

[–] planish@sh.itjust.works 2 points 1 month ago (1 children)

This is clearly meant to be a right triangle. And the distances between the points are the same (because the squares of the coordinate differences are the same), just the directions are different.

If you move 1 unit forward, turn the correct 90 degrees, and then move i units forward, you will end up back where you started.

[–] calcopiritus@lemmy.world 1 points 1 month ago (1 children)

You can't have a distance in a "different direction". That's what the |x| is for, which is the modulus. If you rotate a triangle, the length of the sides don't change.

[–] planish@sh.itjust.works 2 points 1 month ago

The vector from one point to another in space has both a distance (magnitude) and a direction. Labeling the side with i only really makes sense if you say we're looking at a vector of "i units that way", and not at an assertion that these two points are a directionless i units apart. Then you'd have to break out the complex norms somebody mentioned.

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[–] manucode@infosec.pub 47 points 1 month ago (3 children)

1 • 1 + i • i = 1 + (-1) = 0 = 0 • 0

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

[–] blackberrynoseferatu@lemmy.world 28 points 1 month ago

this is why it is still a theorem

[–] suzune@ani.social 22 points 1 month ago (4 children)

I'm so angry at people who think that distances can be imaginary.

[–] lugal@lemmy.dbzer0.com 26 points 1 month ago

Never been together with people and still felt alone?

[–] Xerodin@lemm.ee 24 points 1 month ago (3 children)

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.

[–] spankmonkey@lemmy.world 8 points 1 month 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 7 points 1 month 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.

[–] muntedcrocodile@lemm.ee 1 points 1 month ago

Its another classic case of Euler's Identity

[–] Brainsploosh@lemmy.world 16 points 1 month ago (3 children)

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.

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[–] technocrit@lemmy.dbzer0.com 5 points 1 month ago* (last edited 1 month ago) (1 children)

You're mad at mathematicians for constructing complex valued metrics? It's all just formalism, nothing personal.

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[–] Foofighter@discuss.tchncs.de 4 points 1 month 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.

[–] model_tar_gz@lemmy.world 24 points 1 month ago

You didn’t really expect an imaginary triangle to behave like a real one, did you?

[–] DavidGarcia@feddit.nl 24 points 1 month ago (1 children)

I get it, it's projected on a comlplex sphere. B and C are the same point

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[–] EtherWhack@lemmy.world 16 points 1 month ago* (last edited 1 month ago)

C and B have a wormhole between them

[–] xylogx@lemmy.world 11 points 1 month 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.

[–] propter_hog@hexbear.net 10 points 1 month ago (1 children)

i = 1 is the only logical choice

[–] DragonTypeWyvern@midwest.social 5 points 1 month ago

Literally, this is one of those questions where they're testing logic and your understanding that the figures aren't necessarily representative of physical reality.

[–] i_love_FFT@jlai.lu 9 points 1 month 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.

[–] ShinkanTrain@lemmy.ml 8 points 1 month ago

It gets worse once you start doing trig on it

[–] technocrit@lemmy.dbzer0.com 6 points 1 month ago (1 children)

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 3 points 1 month 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.

[–] Lemmygradwontallowme@hexbear.net 5 points 1 month ago* (last edited 1 month ago) (1 children)

Wish me luck for I'm doing trig test with radians (2 pi rad = 360 ?)

[–] muntedcrocodile@lemm.ee 8 points 1 month ago (2 children)

Radians are the objectivly better way to do angles tho. Just remeber π=180deg and ur right. Btw here is a another brain fuck the units radians/second is just Hz

[–] Lemmygradwontallowme@hexbear.net 3 points 1 month ago (2 children)

Thank you for reminding me!

Btw, Radians/sec = Hz? What is this, physics?

[–] TheOakTree@lemm.ee 2 points 1 month ago* (last edited 1 month ago)

The easiest way to think about it is that 1 full rotation (2*pi radians) in 1 second makes 1 Hz.

The number of rotations made in a second corresponds to Hz in the same way that the number of sine wave periods that fit in a second also represents Hz. This gif does a really good job of showing how rotation relates to sine/cosine waves, which just so happens to help visualize the rad/s -> Hz <- periods/s relationship:

[–] muntedcrocodile@lemm.ee 2 points 1 month ago

Engineering unit maths. Cos angles are unitless so radians/second =1/second=Hz

[–] Zagorath@aussie.zone 1 points 1 month ago

Radians are the objectivly better way to do angles

Yes, and tau is objectively better than pi. Just remember tau = 360°. Which is a full circle, which easier to work with than half a circle.

[–] deikoepfiges_dreirad@lemmy.zip 4 points 1 month ago* (last edited 1 month ago) (1 children)

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.

[–] propter_hog@hexbear.net 1 points 1 month ago (1 children)

But then CB couldn't also be 0; wouldn't it be cos(1 + i)? Or something like that.

[–] deikoepfiges_dreirad@lemmy.zip 3 points 1 month ago

oh I mixed up the points, I meant to say CB is 0 in the end

[–] OrganicMustard@lemmy.world 4 points 1 month ago (1 children)

You can make something like this properly by defining a different metric. For example with metric dl^2^ = dx^2^ - dy^2^ the vector (1, 1) has length 0, so you can make a "triangle" with sides of lengths 1, -1 and 0.

[–] kogasa@programming.dev 2 points 1 month ago (4 children)

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

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[–] solomon42069@lemmy.world 3 points 1 month ago

I feel violated trying to read that in my brain.

[–] RustyNova@lemmy.world 1 points 1 month ago
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