Garfield's proof of the Pythagorean theorem | Geometry | Khan Academy

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  • Опубліковано 1 січ 2025

КОМЕНТАРІ • 126

  • @nickbarton3191
    @nickbarton3191 9 років тому +98

    Just goes to show how boring political meetings are that he had to resort to trig for entertainment.

    • @marcoskano4437
      @marcoskano4437 4 роки тому +1

      Trig is fun even more when you start with cálculos

  • @saturn21207
    @saturn21207 6 років тому +32

    When you think you're eating lasag but you accidentally solve quantum physics

  • @zombieslayer2225
    @zombieslayer2225 5 років тому +32

    Garfield:*Doodles in a meeting.
    Garfield:*Constructs a trapezoid using three triangles.
    Garfield:*Solves the equation.
    Garfield:*Realizes that he just prove the Pythagorean theroem.
    Garfield: :O

  • @Bakmoon
    @Bakmoon 12 років тому +8

    Thank you so much for posting this. This is one of my favorite proofs of the Pythagorean theorem along with the Bhasakra proof and the Chinese proof.

  • @VanBurenOfficial
    @VanBurenOfficial 10 років тому +8

    James A. Garfield was a great man.

  • @javipdr19
    @javipdr19 12 років тому +7

    i've always wondered how a mathematician (amateur or profesional) feels when he finds a proof for something! It must be great, even i got excited watching this video.

  • @Bobyfototube
    @Bobyfototube 10 років тому +12

    Thank u Mr president

  • @Xclann
    @Xclann 12 років тому +6

    Search for "Electron Configuration". That's where the 1s 1s^2 2p^6 3s^2... etc. is explained by Khanacademy (Khan himself).

  • @4gate
    @4gate 9 років тому +19

    beautiful. so simple

  • @AlexandrBorschchev
    @AlexandrBorschchev 4 роки тому +7

    just imagine garfield's face when he found the proof.
    *EUREKA*

  • @longhorn4500
    @longhorn4500 12 років тому +4

    But there are still things that need to be proved such as the sum of the angles of a triangle is 180 and the area of a trapezoid is h * (a + b)/2 :)

  • @viki2133
    @viki2133 8 років тому +21

    Huh... That's quite simple and it's actually using just geometry for the 7th grade.

    • @viki2133
      @viki2133 7 років тому +2

      Shane Yaw ?

    • @Myrus_MBG
      @Myrus_MBG 5 років тому +5

      Dylan Atwater It is a pretty arbitrary to think to create a trapezoid like that, and the solve for the area in two ways. It makes sense why no one would have thought to do that.

  • @callumvanheerden1530
    @callumvanheerden1530 8 років тому +27

    Is it just me or is this easier than the other methods

    • @mausam6101
      @mausam6101 5 років тому +2

      it is/.

    • @marcoskano4437
      @marcoskano4437 4 роки тому +3

      You have seen the square method ? It is much easier than this but this is more fun

  • @smyleylily
    @smyleylily 12 років тому +1

    this is a lot easier than the proof in the book. thumbs up

  • @astroboomboy
    @astroboomboy 12 років тому +1

    Yeah, I was wondering about that, thanks for answering, I'll check it out. Would be neat to use it in lectures!

  • @Funney14096
    @Funney14096 10 років тому +44

    Can Obama do this too?

    • @dalawhether6079
      @dalawhether6079 7 років тому +6

      Funney14096 and Trump?😂😂😂

    • @Burgundian_accel
      @Burgundian_accel 6 років тому +1

      call Mr Donald Trump to attempt for 1 proof.😃

    • @davidgould9431
      @davidgould9431 6 років тому +11

      Trump: "Pythagermmm Theorem - FAKE NEWS"

  • @qszwax57
    @qszwax57 12 років тому +1

    Do you have a video on the difference between theorems and laws?

  • @StevenEncarnacion
    @StevenEncarnacion 12 років тому +2

    awesome...good job Mr Garfield!

  • @thewirelessbrain9331
    @thewirelessbrain9331 8 років тому +14

    Now THAT is a true masterpiece.

  • @Spawnwarrior007
    @Spawnwarrior007 12 років тому +2

    Thanks Sal you're the best bro!

  • @JoeBrenn
    @JoeBrenn 12 років тому +1

    Very cool, I'll admit I wished that I'd seen the end proof coming a little sooner than I did, but it was very interesting nonetheless. Done perfectly to keep peoples' attention too!

  • @Ensign_Cthulhu
    @Ensign_Cthulhu 12 років тому

    That is the neatest and easiest Pythagorean proof I've yet seen.

  • @WiseSquash
    @WiseSquash 5 років тому +2

    this is so beautiful I almost cried :')

  • @Nickuncle
    @Nickuncle 12 років тому

    Honestly, just because you said "mean" for .5(A+B) for the trapezoid I'll actually remember the rule...finally. Thank you.

  • @Funney14096
    @Funney14096 10 років тому +1

    Thanks again!

  • @MonstersSeeMeToo
    @MonstersSeeMeToo 12 років тому +1

    WHAAAT PYTHAGORAS WASN'T REAL EITHER!!! Whats next? Plato never lived in a cave?

  • @lost50
    @lost50 12 років тому

    you could also use opposite reciprocal slopes, i.e. b/a and -a/b, to show that's a 90 degree angle

  • @PillSmasher
    @PillSmasher 11 років тому

    Any possible way you could elaborate further on this proof by extending the top (a) to be equal to the bottom (b), thus creating a rectangle, then solving for the 4th triangle? From this proof, I've came to the conclusion that theta is equal to 30, and that 90 minus theta equals 60, making the a,b triangles 30,60,90 triangles, and the c triangle is a 45, 45, 90 triangle.

  • @bobsagget823
    @bobsagget823 12 років тому +1

    nice

  • @jcc777777
    @jcc777777 12 років тому

    In this instance: B1 = a , B2 = b and H = a+b

  • @doctorcrazydude
    @doctorcrazydude 12 років тому

    I just sat there watching the video, not expection anything impressing, but when he just solved the misterious angle I was like: HOLY SH**! I know that sounds nerdy, but it really blew my mind :D Thanks Sal!

  • @islulison
    @islulison 12 років тому

    i like this one the most, no moving or anything

  • @Gravegore
    @Gravegore 12 років тому

    You are a wizard sir.

  • @zaixhadouken
    @zaixhadouken 12 років тому

    I didn't know Garfield did this. Excellent. +1 for Cats

  • @javed00
    @javed00 12 років тому

    brilliant explanation

  • @andrewreed5743
    @andrewreed5743 12 років тому

    What about using this area for a trapezoid (B1+B2)•H/2

  • @ducameana
    @ducameana 12 років тому

    all the color changing would have been awesome on paper with one of those multicolor clicky pens.

  • @trymore123
    @trymore123 12 років тому

    hello there,
    i am thinking if i could use a little bit of your help..
    i am a constant user of khanacademy website.. i use it a lot but i cant seem to find the video(under chemistry) where you've explained aufbau's principle... am basically having a problem understanding the configuration and how use those 1s 1s^2 2p^6 and others... if you could just help me find the particular video or any related ones... it would be great!!
    thanks!

  • @chitranshnigam4796
    @chitranshnigam4796 3 роки тому

    I just got to know this and this is so cleverrrr

  • @elbay2
    @elbay2 12 років тому

    Yet ANOTHER proof... cool stuff !!

  • @chaitanyanaik641
    @chaitanyanaik641 7 років тому

    Wow😍 too simple

  • @christophersedlak1147
    @christophersedlak1147 8 років тому

    Thanks!

  • @Mintchocolator
    @Mintchocolator 12 років тому

    So interesting!!

  • @sofiagonzalez-nolde9974
    @sofiagonzalez-nolde9974 10 років тому +3

    beautifully simple i love it lol

  • @danieltambunan5409
    @danieltambunan5409 7 років тому +2

    Where did you get 2ab on the left side

    • @4ltrz555
      @4ltrz555 6 років тому +1

      (a+b)^2 = a^2 + b^3 + 2ab

  • @sidyom5068
    @sidyom5068 6 років тому

    A little bit easier of a way to look at it would be to continue the triangle construction all the way around to make a square of side length (a+b) then noting that the crooked square made by the hypotenuses with side length c has area of c^2. Then you can note that [(a+b)^2 - c^2]/4 = ab/2 which leads very naturally into the pythagorean theorem!

  • @XagonogaX
    @XagonogaX 12 років тому

    Could we have a video that proves e=mc squared?

  • @jaywaijy
    @jaywaijy 12 років тому +2

    excellent proof, much more convincing!! Hahaha! I feel like a nerd.

  • @montrast0705
    @montrast0705 8 років тому

    what program are you using for drawing?

  • @maevei-j4798
    @maevei-j4798 10 років тому

    what software do you use to draw and speak at the same time !?!?

  • @trevorstevenson5814
    @trevorstevenson5814 12 років тому

    I still do not understand why those certain positions of triangles have anything to do with the relationship of side measurements in a right triangle.

  • @esmeraldahernandez1709
    @esmeraldahernandez1709 10 років тому

    Thanks Helped me out ! :)

  • @ubrax8161
    @ubrax8161 6 років тому

    Thanks

  • @kremitlol5556
    @kremitlol5556 4 роки тому

    Garfield funny lasagne cat

  • @rauffant
    @rauffant 12 років тому

    Amazing proof.

  • @alizaadnan1367
    @alizaadnan1367 6 років тому +3

    why do u multiply both sides with 2 at 6:56 ???

    • @dataspace8869
      @dataspace8869 6 років тому +5

      To cancel out those "1/2", which makes clearer the proof

    • @thedt7746
      @thedt7746 6 років тому +3

      To get rid of the fraction

  • @beru58
    @beru58 Рік тому +1

    “In the course of my law-reading I constantly came upon the word ‘demonstrate.’ I thought, at first, that I understood its meaning, but soon became satisfied that I did not…. At last I said, ‘Lincoln, you can never make a lawyer if you do not understand what demonstrate means’; and I left my situation in Springfield, went home to my father’s house, and stayed there till I could give any propositions in the six books of Euclid at sight.”
    That was Abe Lincoln on Euclid's Elements. Many important politicians and leaders understood the importance of mathematics. Napoleon is famous for his method to find the centre of a circle with a compass ONLY. NOT compass and straight edge. No wonder the Declaration of Independence is layed out in many respects as the Elements.

  • @groundhogjugglers
    @groundhogjugglers 12 років тому

    Nice!

  • @paul1964uk
    @paul1964uk 12 років тому

    Nice proof.

  • @MCPickaxe
    @MCPickaxe 4 роки тому +1

    i thought garfield was lasagna guy

  • @dsb1763
    @dsb1763 12 років тому

    Garfield was probably as board sitting Congress then as we are now watching CSPAN. Nothing has changed!

  • @charlessmyth
    @charlessmyth 12 років тому

    James Garfield,: Showing that the House of Representatives is sometimes good for something :-)

  • @kelvincheng1833
    @kelvincheng1833 9 років тому

    i just noticed that most of the time, he uses red for side a, blue for side b and yellow for side c in his videos

  • @kafumbla
    @kafumbla 12 років тому

    Lol no he uses a drawing tablet (a Wacom Bamboo tablet). You can find his set-up and gear somewhere on his site

  • @R4G3QUI7
    @R4G3QUI7 12 років тому

    how can he write so clean with mouse ?

  • @morgengabe1
    @morgengabe1 11 років тому

    MS Paint. Use the slanted brushes, not the solid circular ones.

  • @miken5771
    @miken5771 9 років тому

    Genius President.

  • @jacksawhavoc
    @jacksawhavoc 10 років тому

    There is a proof like this where the two trapezoids form a larger square so (a+b)^2 = 4(ab/2) + c^2 . Is Garfield considered to be responsible for this as well?

  • @LiamInviteMelonTeee
    @LiamInviteMelonTeee 4 роки тому

    This reminds me of that clever visual proof on Wikipedia

  • @Klazyo
    @Klazyo 12 років тому

    sooo awesome

  • @morgengabe1
    @morgengabe1 11 років тому +2

    Favourite US President.

  • @64diamonds99
    @64diamonds99 5 років тому

    My math teacher sucks at teaching, so I came here.

  • @GlorifiedTruth
    @GlorifiedTruth 11 років тому

    I read somewhere that Garfield ripped this proof off from Rutherford B. Hayes.

  • @tmjcbs
    @tmjcbs 5 місяців тому

    This is rather similar to the proof with the square with sides a+b

  • @gptrefback
    @gptrefback 12 років тому

    nice and easy (:

  • @rozerincagli4021
    @rozerincagli4021 8 років тому +3

    He was maths teacher before his political career

  • @nurlatifahmohdnor8939
    @nurlatifahmohdnor8939 2 роки тому

    Page 450
    WILLIAM HENRY HARRISON and BENJAMIN HARRISON (grandfather and grandson).

  • @chezbgone-alpha
    @chezbgone-alpha 12 років тому

    If anyone notices, this is just half of bhaskara's proof. :)

  • @adityaaysola9708
    @adityaaysola9708 3 роки тому

    Often times in life , I ask the question "why?" a lot. And, I would like to apply my philosophy to this problem as well. Why did you construct the trapazoid?

    • @staticchimera44
      @staticchimera44 3 роки тому +2

      He had a feeling in his bones.

    • @thecosmos7671
      @thecosmos7671 2 роки тому +1

      No, it's just that we construct something which we know about, because in a two triangles like this he could not create a square,he could have if it were 4 triangles. So ,he just joined the triangles with a line and found it to resemble a trapezoid,as we know one pair opposite sides are parallel in a regular trapezoid so the corresponding sides of the triangles will be the parallel sides and the sum of the bases of the right triangles will be the height of the trapezoid .
      Since we know the formula of area of a trapezoid i.e 1/2(sum of parallel sides*height)
      We just have to equate the area of the trapezoid tp the sum of areas of three triangles ,the two which we already had and the third we constructed which is an isosceles right triangle with the two equal side lengths to be c ,and when finding out the area
      We have( 1/2)ab+(1/2 )ab 1/2(c^2)=1/2(a+b)(a+b)
      [ the third triangle has base and height both as 6]
      Simplifying, we get the result!👍

    • @kerch00
      @kerch00 2 роки тому

      The way to find the area of a trapezoid using its height and bases is proven, so you can build a proof about the bases and height - which are a, b and c here - in a way which can describe their relation, this ends up with the relationship between a, b and c being a^2 + b^2 = c^2

  • @ShadowCloud143
    @ShadowCloud143 12 років тому

    I did not know that.

  • @FrankEgan
    @FrankEgan 12 років тому

    Garfield discovered a new proof for The Pythagorean Theorem while fiddling around as a member of The House of Representatives. Too bad most members of the current House of Representatives are too bussy doing another kind of fiddling around…

  • @astroboomboy
    @astroboomboy 12 років тому

    Do you draw with a mouse?

  • @oriraykai3610
    @oriraykai3610 2 роки тому

    Did he run on this platform and win?

  • @RealistiiC155
    @RealistiiC155 12 років тому +1

    5:10 "now, how can we also fuc- figure out the area?" :P

  • @Linqua2112
    @Linqua2112 12 років тому

    i second more electronics and quantum physics!

  • @danieltambunan5409
    @danieltambunan5409 7 років тому

    Oh i know

  • @cajunmane82
    @cajunmane82 12 років тому

    Your first time hearing about James Garfield is it?

  • @SuperExodus13
    @SuperExodus13 Рік тому

    Apparently he did this when he was bored.

  • @JoshuaIfidi
    @JoshuaIfidi 5 років тому

    James Garfield's proof of the pythagorean theorem was the 5th proof not the first

  • @theimmux3034
    @theimmux3034 4 роки тому

    Wonder if he was just playing around with some geometry and stumbled upon this

  • @alexgold133
    @alexgold133 9 років тому +1

    i am so confused

  • @rakib567
    @rakib567 12 років тому

    Garfield the cat?

  • @abidahasnain2638
    @abidahasnain2638 5 років тому

    Amazingly WoW !
    Thanks for this ...

  • @cobyup10
    @cobyup10 2 роки тому

    *one-halves lying around

  • @daedricwomack7843
    @daedricwomack7843 6 років тому

    I thought dis was gonna be Garfield im an idiot

  • @ereklo
    @ereklo 12 років тому

    5:12 fuck

  • @therealjordiano
    @therealjordiano 12 років тому

    aaaaahhh...... ic... xD ty

  • @klesstwo
    @klesstwo 12 років тому

    he's using a pen with a tablet :)

  • @Puddlewhite1
    @Puddlewhite1 12 років тому

    Not that your statement is bad but... its just so mundane,,,

  • @philz96
    @philz96 12 років тому

    he´s using a pen tablet