Why does π appear in circle area?

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  • čas přidán 19. 01. 2024
  • Explains why the area of a circle is exactly equal to π R^2
  • Věda a technologie

Komentáře • 157

  • @Mike-nf6nf
    @Mike-nf6nf Před 4 měsíci +50

    My main problem with math in physics isn't so much understanding how to go through the equation, but rather, WHY that particular equation is the correct one. These videos help explain why. The color-coding and models are very helpful in making sense of the information. Thanks for all the years of work on your channel!!

    • @EugeneKhutoryansky
      @EugeneKhutoryansky  Před 4 měsíci +7

      Thanks!!!

    • @arinb.756
      @arinb.756 Před 4 měsíci

      If you're a physics student, then it is worth paying far more attention to the relationships and the why. In my experience they always give you references for tests, but more critically, in the workplace, you'll always be able to look up the math. But knowing how the world works allows you to change it and experiment with it in ways no one else has thought of.

  • @bo-dg3bh
    @bo-dg3bh Před 4 měsíci +71

    when a physics guy does mathematical proof, it feels like he’s making sense of things instead of simply stacking up equations

    • @soupisfornoobs4081
      @soupisfornoobs4081 Před 4 měsíci +8

      Even so, these equations have their own sense behind them. There is such a thing as mathematical intuition and it's worth cultivating and applying over physical intuition sometimes

    • @David-bh7hs
      @David-bh7hs Před 4 měsíci +3

      As someone who is a mathematician, sometimes I cringe at physics proofs 😂

    • @eriklopez8770
      @eriklopez8770 Před 4 měsíci +5

      ​@@David-bh7hs Congrats! Now go to your fantasy world so the physicist can cringe at you.

    • @carlhitchon1009
      @carlhitchon1009 Před 4 měsíci +2

      Sounds like you've had some crappy math teachers.

    • @TheBrainn
      @TheBrainn Před 4 měsíci +1

      physics proof videos be like: “just trust me bro, here’s an example”

  • @azathoth00
    @azathoth00 Před 4 měsíci +14

    Love that you can do incredible videos on how tensors work and then do some beautiful proofs on elementary geometry

  • @KVI3I
    @KVI3I Před 4 měsíci +9

    such a beautiful derivation of a very common equation in math and physics, thx!

  • @VlanimationTales
    @VlanimationTales Před 2 měsíci +2

    Beautiful explanation! I know a few proofs for the area of a circle, but I've never seen it presented this way.
    BTW, congrats on one million subscribers! 🎉

  • @tseckwr3783
    @tseckwr3783 Před 4 měsíci +5

    thank you again for your hard work on these excellent videos you produce.

  • @e.b.1115
    @e.b.1115 Před 4 měsíci +6

    But where does pi come from in the circumference?
    I took those triangle areas and came up with the limit
    Lim n-->inf (n)(r*sin(pi/n))(r*cos(pi/n))
    x=pi/n
    Lim x-->0 (pi/x)(r^2sin(x)cos(x))
    [Lim x-->0 pi*r^2][Lim x-->0 sin(x)/x][Lim x-->0 cos(x)]
    (Pi*r^2)(1)(1)
    Pi*r^2
    But the pi still comes out of nowhere lol

    • @EugeneKhutoryansky
      @EugeneKhutoryansky  Před 4 měsíci +5

      That is the definition of pi: It is the circumference divided by the diameter.

    • @e.b.1115
      @e.b.1115 Před 4 měsíci

      Ah that's true
      I'm still not satisfied for some reason XD
      Love your videos!

  • @VADemon
    @VADemon Před 4 měsíci +2

    As that other comment asking about where π comes from in the circumference, I expected some form of introduction through the ways the ancient Greeks might've derived π.

    • @EugeneKhutoryansky
      @EugeneKhutoryansky  Před 4 měsíci +3

      That is the definition of pi: It is the circumference divided by the diameter.

  • @feynstein1004
    @feynstein1004 Před 4 měsíci +4

    This seems a bit circular (heh). So in essence, this happens because the area of a circle is R/2 times bigger than its circumference.

    • @IslandForestPlains
      @IslandForestPlains Před 4 měsíci

      Yeah I also expected a video that explained why exactly pi is the value it is, especially after Eugene started with showing that the area of a circle is somewhat smaller than 4. An information that wasn't needed for the further explanation, as pi was then introduced as c/d. So given the question in the heading, in essence pi appears in the circle area because it appears in the circle circumference.

    • @feynstein1004
      @feynstein1004 Před 4 měsíci +1

      @@IslandForestPlains Yeah it's a bit of circular logic 😅

  • @mr.thermistr9903
    @mr.thermistr9903 Před 4 měsíci +2

    You are doing a great job. 👍
    Never stop uploading.

  • @KaliFissure
    @KaliFissure Před 4 měsíci +3

    What's cute is that if you have a circle with radius Pi, the circumference is 2Pi² and the area is Pi³. The area of a sphere of radius Pi is 4Pi³ and the volume 4/3 Pi⁴

    • @lindt3787
      @lindt3787 Před 4 měsíci +1

      Interesting. Strictly speaking, length, area and volume are magnitudes expressed in different units, so comparing their raw numeric values has no meaning. But interesting nonetheless.

    • @KaliFissure
      @KaliFissure Před 4 měsíci +2

      @lindt3787 yes. A numerical trick.
      But after doing a series of investigations into sphere/circle volume area length investigations that popped out. Like a math pun.

  • @Mysoi123
    @Mysoi123 Před 4 měsíci +12

    Absolutely beautiful! ❤

  • @klumpid6097
    @klumpid6097 Před 4 měsíci +5

    The music is just as awesome as the content!

    • @zh84
      @zh84 Před 4 měsíci

      Beethoven's "Moonlight" sonata.

  • @farhanhassan1865
    @farhanhassan1865 Před 4 měsíci +6

    Always waiting for video by Eugene

  • @mateuszpraseek6733
    @mateuszpraseek6733 Před 4 měsíci

    Elegant proof :D
    Coincidentally I was wondering when will You upload Your next full-length video, and I am happy You did :D but its too short for me to be fully satisfied, but it's better than nothing! :D I love Your channel and hope for more videos

    • @EugeneKhutoryansky
      @EugeneKhutoryansky  Před 4 měsíci

      More videos are on their way. I can never predict the date of my next video. Thanks.

  • @Ali2599
    @Ali2599 Před 3 měsíci

    Thank you very much because you are doing hard work in producing these amazing and useful videos. Therefore, I hope that this great channel will continue and we are always waiting for everything new.

  • @erdaly4557
    @erdaly4557 Před 4 měsíci +9

    Eugene. you are a role model! Thank you so much

  • @vigneshsurya2504
    @vigneshsurya2504 Před 4 měsíci +5

    Very clearly explained.👏👏👏

  • @zacharywong483
    @zacharywong483 Před 4 měsíci

    Fantastic explanations, as always!

  • @roaster591
    @roaster591 Před 4 měsíci +1

    I use diameter squared times .785 for area of a circle, on the job related to pipe flow rate

  • @alihakimtaskran7809
    @alihakimtaskran7809 Před 4 měsíci +2

    Eugene used to share videos on complex topics like quantum mechanics and general relativity. Could you share more about those complex topics?

  • @physicslover1950
    @physicslover1950 Před 4 měsíci

    Wow, my mentor that was brilliant.. I am anxiously waiting for your video on gravitational microlensing... Specially the xLxS models of gravitational microlensing where x are random numbers.

  • @yodaqwq
    @yodaqwq Před 4 měsíci +3

    But how do we know that the ratio of the circumference and diameter is the same for all circles?

    • @EugeneKhutoryansky
      @EugeneKhutoryansky  Před 4 měsíci +3

      When you scale any object, all the dimensions of the object scale in proportion.

    • @IslandForestPlains
      @IslandForestPlains Před 4 měsíci

      It's like a map. The ratio of distances is the same as in reality. So if on the map street A is twice as long as street B, you know that it is likewise in the real world.

  • @anitakhandelwal307
    @anitakhandelwal307 Před 4 měsíci

    Wow..😊welcome mam,I have been waiting since long time..

  • @Rationalific
    @Rationalific Před 4 měsíci +1

    It's an amazing look to see why things are the way they are, rather than just taking them for granted as the way they are. The explanation was amazing. As for my brain, I could barely keep up, and this isn't rocket science. My mind boggles at those like the creator of this video who can not only easily understand but also explain these ideas so well. And then there are those who actually figured these things out....the giants upon which we and all of modern society stands (mostly aloofly and ungratefully).

  • @namelname2448
    @namelname2448 Před 4 měsíci +3

    Useful information.

    • @EugeneKhutoryansky
      @EugeneKhutoryansky  Před 4 měsíci

      Thanks.

    • @namelname2448
      @namelname2448 Před 4 měsíci

      You're Welcome!, please concentrate on Geometry,some of us need it in our work.@@EugeneKhutoryansky

  • @LawatheMEid
    @LawatheMEid Před 4 měsíci +1

    C=π x diameter
    This equation come from arc length equation which is:
    A = angle of the arc in radian x radius
    So:
    C = 2π x r

  • @arinb.756
    @arinb.756 Před 4 měsíci +1

    Off topic but what is the background music used in the video on Mutually Assured Destruction?
    Thank you!

    • @EugeneKhutoryansky
      @EugeneKhutoryansky  Před 4 měsíci +4

      Ride_of_the_Valkyries_by_Wagner
      Moonlight_Sonata_by_Beethoven
      Both from the free CZcams audio library

    • @arinb.756
      @arinb.756 Před 4 měsíci +1

      @@EugeneKhutoryansky Thanks! the music certainly makes the videos more engaging and dramatic, especially when you cover the philosophical implications of some of these topics.

  • @ThirdOneness
    @ThirdOneness Před 4 měsíci +1

    You are the best for me ,
    please try to demonstrate addition formula for secant and cosecant
    Why : secant (a+b) = sec a sec b csc a csc b / csc a csc b - sec a sec b ,
    and so on ...

  • @PabloBatistaArq
    @PabloBatistaArq Před 4 měsíci +1

    I did calculus in college and I had forgotten about this 😅

  • @LawatheMEid
    @LawatheMEid Před 4 měsíci

    Waiting for video about subatomic world.. it will be magnificent in your way of introducing.

    • @EugeneKhutoryansky
      @EugeneKhutoryansky  Před 4 měsíci +2

      I already have many videos on that topic. They are available in my playlist below:
      czcams.com/play/PLkyBCj4JhHt-uU7uZECW3aZx8g1klRg8_.html&si=Sqi1dmPghrgPe0ZH

  • @ayushsharma8804
    @ayushsharma8804 Před 4 měsíci

    Eugene do you have any plans about Classical Hamiltonian mechanics? Seems to be an empty niche on CZcams, can't seem to find any videos

    • @EugeneKhutoryansky
      @EugeneKhutoryansky  Před 4 měsíci

      That is on my list of topics for future videos. Though, I already have a video on Lagrangian Mechanics at czcams.com/video/EceVJJGAFFI/video.html

  • @morkovija
    @morkovija Před 4 měsíci

    Absolutely brilliant.

  • @skrishna6336
    @skrishna6336 Před 4 měsíci +3

    Than why circumference= pi × diameter?

    • @EugeneKhutoryansky
      @EugeneKhutoryansky  Před 4 měsíci +1

      That is the definition of pi: It is the circumference divided by the diameter.

    • @skrishna6336
      @skrishna6336 Před 4 měsíci +1

      @@EugeneKhutoryansky Perfect. Thanks for the clarification.

  • @antoniomoyal
    @antoniomoyal Před 4 měsíci +2

    The proof that mathematical objects cannot be material. As matrer cannot be divided infinitely.

  • @TheIvalen
    @TheIvalen Před 4 měsíci +2

    I followed you until you used pi in the circumference. It’s like defining a word in a dictionary by using the word itself.

    • @EugeneKhutoryansky
      @EugeneKhutoryansky  Před 4 měsíci +1

      That is the definition of pi: It is the circumference divided by the diameter.

  • @RobertoCerv90
    @RobertoCerv90 Před 3 měsíci

    Hi Eugene. Nice 2024. I'm considering your student of physics, only because I learn more deeply some terms of quantum theory.
    I will be incredibly grateful if you can, on your stupendous way to make us understand, more deeply the "Quiral". I can understand the spin on electrons and can be up or down, and that's because it's 1/2 to complete orbits, essential for atoms. And also haves a deal with the stable number of neutrons on atoms to completed. I understand. Also the interaction with higgs with electrons.
    But I don't know why that interaction, his repercution on atoms and if it's a necessary have left and right pairs of quiral particles on electron orbitals, and off course the knowledge you have of other properties unknown for most of us...
    It will amazing. Truly I admire your channel, and all to do for the ones who haves tis passion with the nature, and finds out all creators never go so profound like you. And you end finish knowing the same. Of all those.
    My best wishes from Guadalajara... A City on the state of Jalisco who belongs to Mexico 🇲🇽
    Send you an “e-💐"

    • @EugeneKhutoryansky
      @EugeneKhutoryansky  Před 3 měsíci

      I explain why each electron orbital can accommodate two electrons of opposite spin in my video on the Pauli Exclusion Principle at czcams.com/video/Zlp2GQ3OLeE/video.html
      Thanks!

  • @pankajtomar2358
    @pankajtomar2358 Před 4 měsíci

    Excellent vedio. Nice explained. I got interest in physics due to your channel in my age of 50 .
    Regards

    • @EugeneKhutoryansky
      @EugeneKhutoryansky  Před 4 měsíci

      Thanks. I am glad you liked my video and I am glad I made you interested in physics.

  • @trout3685
    @trout3685 Před 4 měsíci

    Using radii in a sqaure was a new concept for me.

  • @nohjrd
    @nohjrd Před 4 měsíci

    Excellent video

  • @RobertoCerv90
    @RobertoCerv90 Před 3 měsíci

    And that's the truly reason why the Area it π*r².
    The curious fact is that, it's the first time I known that before. And I'm very sure, If I had seen it at school, I would have understood. And I wouldn't have hated the exercises on circle areas so much 🤭

  • @chlodnia
    @chlodnia Před 4 měsíci

    I kind of look like a triangle. Thanks for the video

  • @kv2893
    @kv2893 Před 4 měsíci

    Great video!

  • @peshalbasnet2425
    @peshalbasnet2425 Před měsícem

    Thank you so much

  • @anton.w1b
    @anton.w1b Před 4 měsíci

    Thats a cool video

  • @Singapukodama
    @Singapukodama Před 3 měsíci

    explaining the area of moon with moonlight sonata

  • @prashantsharma7788
    @prashantsharma7788 Před 4 měsíci +2

  • @TheClonerx
    @TheClonerx Před 4 měsíci +3

    Ok but now why is there a pi in the circumference

    • @EugeneKhutoryansky
      @EugeneKhutoryansky  Před 4 měsíci +2

      That is the definition of pi: It is the circumference divided by the diameter.

    • @Elias-dz7zx
      @Elias-dz7zx Před 4 měsíci

      Good point. The video attempts to explain how π appears in the circle but is based on the definition of π that is the ratio of circumference to diameter. So the initial question and the video is pointless. It is as if it defines a word using the word in the definition. Loop!

    • @EugeneKhutoryansky
      @EugeneKhutoryansky  Před 4 měsíci +2

      No, it is not pointless. It shows why the area of a circle is related to its circumference, hence this explains why the area is related to pi.

    • @ayushsharma8804
      @ayushsharma8804 Před 4 měsíci +1

      ​@@Elias-dz7zxthe video asks why pi appears in circle *area*, the definition of pi in respect to the circumference is irrelevant here

    • @Elias-dz7zx
      @Elias-dz7zx Před 4 měsíci

      @@ayushsharma8804 this is exactly why it appears to area

  • @bharathreddygudibandi492
    @bharathreddygudibandi492 Před 4 měsíci

    Greatest video.

  • @RobertLeyland
    @RobertLeyland Před 4 měsíci

    Which is why we should be using TAU instead of PI, as almost all formula involving circles, trig or,rotations etc end up using 2*PI … explanations like this would also make more intuitive sense.
    Sadly centuries ago measuring the diameter of a circle was easier than measuring the radius, so we are stuck with PI

  • @arandomguy777
    @arandomguy777 Před 21 dnem

    Physicists: Area = 3 R^2

  • @WFSJUBTWPTMJCFSBCJU
    @WFSJUBTWPTMJCFSBCJU Před 4 měsíci

    what song is this again?

    • @EugeneKhutoryansky
      @EugeneKhutoryansky  Před 4 měsíci

      Moonlight_Sonata_by_Beethoven from the free CZcams audio library.

  • @bobobricklayer
    @bobobricklayer Před 4 měsíci +1

    Dude, the world of education needs you.

  • @simpleman283
    @simpleman283 Před 4 měsíci

    Even I can understand that.
    Thanks.
    1/24/2024

  • @kagannasuhbeyoglu
    @kagannasuhbeyoglu Před 4 měsíci

    👍

  • @mrhoho
    @mrhoho Před 4 měsíci

    nice vid.

  • @samwisegamgee4659
    @samwisegamgee4659 Před 4 měsíci +1

    Great Proof! I hit *LIKE* 3 times.

  • @namelname2448
    @namelname2448 Před 4 měsíci

    How many perfect triangles in 1 circle?,thank you

    • @EugeneKhutoryansky
      @EugeneKhutoryansky  Před 4 měsíci

      As the number of slices approaches infinity, each slice approaches a perfect triangle.

    • @namelname2448
      @namelname2448 Před 4 měsíci

      I see,thank you for answering.@@EugeneKhutoryansky

  • @user-yo5vk2bc5m
    @user-yo5vk2bc5m Před 4 měsíci

  • @abhisheksinghyadav7887
    @abhisheksinghyadav7887 Před 4 měsíci

    Hello sir I'm from India.🇮🇳

  • @Chicky-yy7nk
    @Chicky-yy7nk Před 4 měsíci

    the goat

  • @nirmalmishra6404
    @nirmalmishra6404 Před 4 měsíci

    Eugene, what's your qualification btw?

  • @sergiydmitruk145
    @sergiydmitruk145 Před 4 měsíci

    Please, explain why electricity from power bank moves only in one direction to accumulator of telephone!!! Why not in reverse direction???

    • @EugeneKhutoryansky
      @EugeneKhutoryansky  Před 4 měsíci +2

      I explain this in my video "AC to DC Voltage Rectifiers" at czcams.com/video/J8A6QUxfk8c/video.html

  • @Lolwutdesu9000
    @Lolwutdesu9000 Před 4 měsíci

    The first two minutes of this video are satire, right?

  • @ajaybisht922
    @ajaybisht922 Před 4 měsíci

    Make video on physics topics

    • @EugeneKhutoryansky
      @EugeneKhutoryansky  Před 4 měsíci

      More physics videos are on their way.

    • @ajaybisht922
      @ajaybisht922 Před 4 měsíci

      @@EugeneKhutoryansky thanks for , this immense value you have provide from very long time ❤️❤️.

  • @taritkumarray2614
    @taritkumarray2614 Před 4 měsíci

    But please explain why circumstances of a circle is equal to 2πr. How come π fits in to solve the problem of measuring the circumference of a circle?
    When explaining definition of "π" You also said so diameter of a circle has something to do with ascertaining the area of a circle ? How he thought so when the person who found this formula first of area of a circle ? He could have thought of solving the problem in terms of diameter, radius, circumference only? Why the idea of π came to his mind?

    • @EugeneKhutoryansky
      @EugeneKhutoryansky  Před 4 měsíci +1

      That is the definition of pi: It is the circumference divided by the diameter.

    • @taritkumarray2614
      @taritkumarray2614 Před 4 měsíci

      @@EugeneKhutoryansky thanks.but we all know that. The crux of the matter is how come the idea of a weird thing such as π did come in ascertaining a formula.

    • @lindt3787
      @lindt3787 Před 4 měsíci

      ​@@taritkumarray2614You can rephrase the question in the title as "Why does the same factor appear in the circle circumference and area formulas"

    • @taritkumarray2614
      @taritkumarray2614 Před 4 měsíci

      @@lindt3787 Yes thank you. Please upload a new video on this question next time.
      Why and how on earth did come the idea of π?

    • @lindt3787
      @lindt3787 Před 4 měsíci

      ​@@taritkumarray2614 I was trying to help you understand the point of this video. Most people will consider that what is shown here is not as obvious as you think.

  • @veryveryveryvery161
    @veryveryveryvery161 Před 4 měsíci

    Я понимаю так, что число пи - это характеристика самого пространства. Пока мы на прямой - работают рациональные числа. Чуть отойдем во второе измерение - появляются иррациональные - корень из двух в случае гипотенузы треугольника 1х1 или пи в случае длины окружности.

    • @TheDelwish
      @TheDelwish Před 4 měsíci

      данное значение отношения длины окружности к диаметру, которое названо пи, - безусловно характеристика евклидова пространства (в других геометриях оно просто другое). насчет отойдем в другое измерение, и да и нет, т.е. с одной стороны ничто не запрещает быть всему множеству действительных чисел на прямой, собственно есть аксиоматики чисел которые и работают на прямой, а есть типа Дедекиндовых сечений. это просто вы для наглядности континуума вещественных чисел представляете примеры с большим числом измерений. ибо проще. но строго говоря можно расширить числа на иррациональные и трансцендентые даже без всяких таких вещей. для прямой и вообще для математики нет никакой принципиальной разницы между 1 и корнем из 2. просто вам кажется что обозначение первого объекта в виде литеры "1" вам почему-то более понятно. но строго говоря непрерывность такая сложная штуку, что понять ее сложно вне зависимости что вы видите на прямой, 0.(9), 1.(0) или 1.(0)1

  • @chudleyflusher7132
    @chudleyflusher7132 Před 4 měsíci +1

    You must be new around here…

  • @firstnamesurname6810
    @firstnamesurname6810 Před 4 měsíci

    Eugene from walking dead 😂

  • @ucngominh3354
    @ucngominh3354 Před 4 měsíci

    hi

  • @RandomNullpointer
    @RandomNullpointer Před 3 měsíci

    This video is lacking some necessary animation, for moving equation parts around...

  • @robbiekavanagh2802
    @robbiekavanagh2802 Před 4 měsíci

    Wait has this channel been an ai voice this whole time?

    • @EugeneKhutoryansky
      @EugeneKhutoryansky  Před 4 měsíci +1

      All my videos are narrated by my friend, Kira Vincent. This is stated on the screen at the end of almost all my videos, including this one.

    • @robbiekavanagh2802
      @robbiekavanagh2802 Před 4 měsíci

      @@EugeneKhutoryansky I have actually been watching this channel for longer than ai voices have been good! I was mostly kidding around but honestly sometimes I don't know what's real!

  • @robertbloch1063
    @robertbloch1063 Před 4 měsíci +3

    Sorry, the background music is so distracting...

    • @EugeneKhutoryansky
      @EugeneKhutoryansky  Před 4 měsíci +7

      If it bothers you that much, you can turn off the sound and turn on the subtitles.

    • @celio_cabrera
      @celio_cabrera Před 4 měsíci +5

      I like it so much😮😮

    • @Nickname006
      @Nickname006 Před 4 měsíci +3

      It is literally part of the style of this channel.

    • @lindt3787
      @lindt3787 Před 4 měsíci +4

      Distracting from what? The music is an important part of these videos...

    • @robertbloch1063
      @robertbloch1063 Před 4 měsíci

      @@EugeneKhutoryansky Thanks for the most constructive feedback. Feels a bit strange, but works. Cheers!