Does this mean that, since division of a length by any positive number is possible using these tools, we can divide the circle into any natural number of equal areas with this method?
@MathVisualProofs2 жыл бұрын
Give it a try with 8 pieces and see what you get :)
@jakobr_2 жыл бұрын
@@MathVisualProofs Yep, I just confirmed it. The reason this works is that the area of a semicircle is quadratic in r. Stepping into the world of discrete calculus, the difference between successive terms of this quadratic sequence is a linear function of r. This difference sequence corresponds to the “upper” part of each slice. Because this sequence of areas is linear, we can take the reverse of this sequence (the rotated “lower” semicircle), pair up matching pieces, and each slice now has the same area, because the constant amount the area changes in the upper semicircle is exactly negated by the change in the lower semicircle.
@MathVisualProofs2 жыл бұрын
@@jakobr_ 😀👍
@jamesparsley57962 жыл бұрын
@@jakobr_ Isn't it a linear function of r^2?
@jakobr_2 жыл бұрын
@@jamesparsley5796 The difference between successive terms in a quadratic (in r) sequence is linear (in r)
@debblez2 жыл бұрын
oh thats nice.
@MathVisualProofs2 жыл бұрын
Thanks!
@SuperDydx2 жыл бұрын
Real nice!
@MathVisualProofs2 жыл бұрын
@@SuperDydx thanks!
@estherclawson6876 Жыл бұрын
69th like.... nice to your nice.
@jercki722 жыл бұрын
I think it would have been interesting to explain how you can cut the diameter in 7 pieces using the straight edge and compass, but I really like the conciseness of this video
@MathVisualProofs2 жыл бұрын
Yes. That would have made the video quite a bit more complicated in the middle and would have possibly confused the issue. There have been enough comments about this that maybe I should do an auxiliary one showing how to do that division. Thanks for the feedback!
@saschabaer33272 жыл бұрын
While you can construct any rational number length (in particular 1/7), the easier approach is to just take a circle of diameter 7 instead, starting with a given length of 1.
@jercki722 жыл бұрын
@@MathVisualProofs I also realized that you didnt really dive into why a pentagon was constructible and not a heptagon, which I kind of took for granted because I was taught this a long time ago while I only realized how to multiply and divide recently, even though it's arguably easier. I see why it doesnt make much sense to include it here since explaining everything would change the video completely
@MathVisualProofs2 жыл бұрын
@@jercki72 Yes. That is a good idea though. Maybe I can do a construction of the pentagon and a dividing into n pieces video. Thanks!
@dougsholly93232 жыл бұрын
I can see how you can create a circle with a diameter of 7x by drawing a line, then using the compass pick a length, and repeat it 7 times on a line. This becomes your diameter. Then bisect your line using the compass giving you a radius where you can complete your circle. But that is backwards. I would also like to see how you divide the diameter into 7. Edit: I saw the solution in a post below. Fantastic. It's funny because the solution is basically doing exactly what I said except creating 2 parallel lines of 7 segments, then you transfer those proportions to the fixed line. Very interesting.
@TheMCMaster2 жыл бұрын
I think all of the #some2 videos have been great, but there is just something so nice about a short, but elegant video like this
@MathVisualProofs2 жыл бұрын
Thanks! But Whoops. I copied and pasted a title and included the # here. I'll remove it because my official SoME submission is a different video. Maybe I should have made it this one...
@zhinkunakur47512 жыл бұрын
@@MathVisualProofs was that really a mistake? ; )
@MathVisualProofs2 жыл бұрын
@@zhinkunakur4751 Yes - and it's fixed. I created the videos in the same time frame and wasn't sure which one to submit to SoME :) It appears maybe I should have submitted this one because people like it better :)
@pamplemoo Жыл бұрын
Pmmpm
@AllThingsPhysicsYouTube2 жыл бұрын
This is brilliant and beautiful! Very nicely done! At first glance, it's not at all obvious how I would divide the diameter into 7 equal segments, but I'll take your word for it that it can be done.
@MathVisualProofs2 жыл бұрын
Not obvious at all. But you can divide a line into n parts for any positive integer n with straightedge and compass. Here is the technique: www.mathopenref.com/constdividesegment.html
@talinuva2 жыл бұрын
Step 1: draw a line starting at one of the endpoints (aside from needing to not be parallel with the diameter, it doesn't matter which direction) Step 2: mark seven equally spaced points along that line Step 3: draw a line from the farthest point to the other endpoint Step 4: draw lines parallel to the one drawn in step 3 from the other points
@AllThingsPhysicsYouTube2 жыл бұрын
@@MathVisualProofs Got it...not obvious, but also not that hard to understand.
@jacobcowan35992 жыл бұрын
If I'm not mistaken, another construction would be possible by first drawing a line through an offset point C roughly parallel to the original AB (I don't think it's a requirement, but I'm not working with the most rigor here) Then make equidistant marks on the line through C, finishing with point D Then construct line AC and BD so that they intersect at a new point E Then connect each of the points on CD to E, and where they intersect like AB will also be equidistant (like parallel lines running to a vanishing point in a renaissance art piece)
@Extramrdo2 жыл бұрын
@@AllThingsPhysicsKZfaq Less rigorous, more accessible: "make up two parallel lines out of X segments, draw vertical lines between the segments of the two lines, and so any slice of these new rectangles has the vertical lines equally distant. Construct it smart from the beginning so that the line you wanted to divide is one such slice." Because if you slice a metal fence, any angle you cut it, the tips of the posts will be equidistant.
@the_hidden_library2 жыл бұрын
But the real question is: can you also make a NON-regular square?
@MathVisualProofs2 жыл бұрын
Haha! I should have fixed that. But left it. Re-recording audio isn’t my fave :)
@AJMansfield12 жыл бұрын
@@MathVisualProofs wdym, don't you know about the _other_ squares?
@MathVisualProofs2 жыл бұрын
@@AJMansfield1 If you meet the other squares, let me know :)
@sachs62 жыл бұрын
In some surfaces yes, a quadrilateral may have all sides with the same length, all angles right, and still have no vertice transitivity.
@screambmachine2 жыл бұрын
i think times square is not a regular square
@johnchessant30122 жыл бұрын
Very nice! You could alternatively mark points on the radius at distances sqrt(1/7), sqrt(2/7), sqrt(3/7), ... and draw concentric circles, but this method is so much more elegant!
@kingbroseph97732 жыл бұрын
That's what I was thinking the pizza with 7 slices bahaha
@fejfo65592 жыл бұрын
but how do you construct sqrt(1/7) with straight edge and compas?
@jkid11342 жыл бұрын
@@fejfo6559 pythagorean theorem is pretty good for this
@jmiki892 жыл бұрын
@@fejfo6559 you can construct the square root of any given length either the geometric mean theorem ( en.wikipedia.org/wiki/Geometric_mean_theorem ) or the intercept theorem ( en.wikipedia.org/wiki/Intercept_theorem with the segments on the two rays being 1 + s and s + x, respectively). Both are fairly simple methods, personally I lean toward to the GMT for some reasons. Alternatively, you can construct sqrt(7) by a series of right-angled triangles starting with the classical 1-1-sqrt(2) triangle (the half of a unit square) then the first leg of each next triangle is the hypotenuse of the previous one and the second leg is always 1, and then you can divide it by 7. Well you can start the series with the 1-2-sqrt(5) triangle since 2 is the largest whole number of which square is smaller than 7, but this would be much more effort than either of the first two, I think. Still, I like the (mental) image of the resulting "spiral" of triangles. On the other hand, if you start from the 1-1-sqrt(2) triangle, you'll get all the square roots up to 7 which would be useful for scaling the sqrt(1/7) if you want to construct sqrt(2/7), sqrt(3/7), sqrt(4/7) etc as well, like in the original comment suggested.
@fenrisredacted28702 жыл бұрын
I wish I had seen this when I had a customer who wanted their pizza in 7 slices lmao
@mikhail_from_afar2 жыл бұрын
But how do you divide a line segment into seven equal parts with a straight edge and a compass? Am I missing something obvious?
@MathVisualProofs2 жыл бұрын
It’s not obvious but here is a source that gives the idea: www.mathopenref.com/constdividesegment.html
@tombackhouse91212 жыл бұрын
Create seven end to end line segments of equal length to make a line segment of seven equal sections, with one end positioned at the start of the line segment you want to divide, and point it off to one side so the two are arranged like a V. Add another line segment joining the ends of the v to make a triangle. Parallel to this new line segment, draw another line segment from each of the nodes joining the seven equal segments you drew earlier, such that the new lines intersect the original line segment which was to be divided. The intersection points divide the initial line segment evenly into seven. It's not obvious no :)
@sweetcornwhiskey2 жыл бұрын
Alternatively to dividing a line segment into 7 equal parts is to start with a short line segment, build 6 additional line segments onto the end of it, and construct the circle from these. Technically it's not dividing the circle into 7 parts, but I think this counts.
@MichaelRothwell12 жыл бұрын
This technique has been known for quite some time. It is Proposition 9 of Book VI of Euclid's Elements, written c. 300BCE. See aleph0.clarku.edu/~djoyce/java/elements/bookVI/propVI9.html On the other hand, the fact that you can't construct a regular heptagon with only a compass and straight edge has only been known since 1837, thanks to the Gauss-Wentzel theorem. This states that a regular n-gon can be constructed with compass and straightedge if and only if n is the product of a power of 2 and any number of distinct Fermat primes (including none). The Fermat Primes are the primes of the form 2^2^n+1, where n is a natural number, such as 3, 5, 17, 257, 65537. These are the only Fermat primes known. So after the regular pentagon, the next few odd-sided regular n-gons you can construct are for n=15, 17, 51, 85, 255 and 257. See en.m.wikipedia.org/wiki/Constructible_polygon
@MathVisualProofs2 жыл бұрын
@@sweetcornwhiskey Is true that shows the length 7 is constructible, but it does take a bit more to show that 1/7 is constructible. But you are right that it is perhaps technically correct because I didn't say you had to start with a particular circle :)
@dabbopabblo2 жыл бұрын
After being separated those don't even look like they should fit together to make a circle but the proof is all there, incredible
@MathVisualProofs2 жыл бұрын
Right? Pretty cool.
@trashtrash2169 Жыл бұрын
Well, they do, but sure.
@sachs62 жыл бұрын
Although you've spoiled the answer in the video thumbnail, the idea is so brilliant I had to watch it. Thank you for bring this up. I wonder which areas are constructible given a unit area circle, besides the rationals. Wow!
@MathVisualProofs2 жыл бұрын
😀 thanks! Sorry to spoil it early. The KZfaq thumbnail game is beyond me and the hardest part about having a channel. I just want to share some visual math ideas :)
@sachs62 жыл бұрын
@@MathVisualProofs Maybe it was for the best, who knows, without the spoiler I could just think "No." and move on thinking it was just a video about the unconstructability of the heptagon.
@MathVisualProofs2 жыл бұрын
@@sachs6 good point!
@RainShinotsu2 жыл бұрын
Honestly, I like that the thumbnail showed the answer. At a glance, it allows the viewer to see the answer while scrolling through, yet they can still watch the video to learn why it's the answer. In this case too, the squiggly segments can pique the viewer's interest because thet might not make a lot of sense without the proof.
@MathVisualProofs2 жыл бұрын
@@RainShinotsu Thanks!
@Archisphera2 жыл бұрын
Stay away from my pizza.
@thomasolson7447 Жыл бұрын
I was just thinking of perspective vanishing points in art. That stuff is all about preserving angles. These lines that represent length can be vectors. That being said, any vector can be any unit. So, a perspective vector doesn't have to represent length, it can be anything.
@MathVisualProofs Жыл бұрын
👍
@mathflipped2 жыл бұрын
Great visual proof!
@MathVisualProofs2 жыл бұрын
Thanks!
@cat-astrophe86972 жыл бұрын
My 6 friends are going to love it when I pull this trick out to cut a pizza for us.
@MathVisualProofs2 жыл бұрын
I’d like to see it done!
@GODDAMNLETMEJOIN2 жыл бұрын
The way I'd tackle this problem would be to first construct a line segment with length root 7. From there one would construct concentric circles, one with radius 1 and one with radius root 7. The space between the outer circle and the inner circle can then be divided in six leaving one circle and six arches of equal area.
@MathVisualProofs2 жыл бұрын
Is a good way!
@TitoTheThird2 жыл бұрын
Beautiful!
@MathVisualProofs2 жыл бұрын
Thanks! 😀
@begerbingchilling Жыл бұрын
Thats actually beautiful
@MathVisualProofs Жыл бұрын
😀
@updown15272 жыл бұрын
Wow, love the solution 😀 I was always into math/physics, so it’s kinda fun 😉 Hope for more videos and keep up a good work 👍
@MathVisualProofs2 жыл бұрын
Thanks! Check out my catalog for more visual proofs/visualizations. :)
@quantumgaming91802 жыл бұрын
Amazing. What other regular polygons can we NOT make using the classical tools?
@MathVisualProofs2 жыл бұрын
That’s a good question! Give a search for constructible regular polygons and you’ll find out. There are lots that aren’t. :)
@jakobr_2 жыл бұрын
According to wikipedia en.wikipedia.org/wiki/Constructible_polygon#Detailed_results_by_Gauss's_theory, an n-gon is constructible when n is a product of a power of 2 with any combination of the numbers 3, 5, 17, 257, and 65537. All other n-gons are not constructible. So, for example, a 64*5*257-gon is constructible, while a 25-gon is not. If we discover any other “Fermat primes”, those primes will be added to the list with 3,5,etc.
@MathVisualProofs2 жыл бұрын
@@jakobr_ exactly! Makes the Fermat primes even more intriguing :)
@Leech.Lattice Жыл бұрын
This is beautiful, for years I watch 3blue1brown videos and your videos give me the same vibe. I love it keep up the great videos
@MathVisualProofs Жыл бұрын
Thanks! I am using his amazing software so it makes sense it would give that vibe :)
@dougsholly93232 жыл бұрын
Very interesting solution, but by your first few examples, I (incorrectly) assumed the final shape would be a pie piece. Tricky :)
@MathVisualProofs2 жыл бұрын
Yes. Didn’t mean to mislead. If you could do a pie shape I think you could do the impossible and construct the heptagon :)
@dougsholly93232 жыл бұрын
@@MathVisualProofs I remember back in school my teacher tossed out the "trisect an angle" challenge with a compass and a straight edge. I wanted so bad to find a solution :)
@MathVisualProofs2 жыл бұрын
@@dougsholly9323 love that! Even though it’s impossible a challenge like that can really inspire. Speaking of, at some point I will have a video that shows how to trisect an angle…. But it needs one extra tool that isn’t classical :)
@eternalfizzer Жыл бұрын
That's gorgeous!
@MathVisualProofs Жыл бұрын
😄
@leecrawford6560 Жыл бұрын
I wish I was shown this when I was in junior high/ high school man, this would have been awesome
@MathVisualProofs Жыл бұрын
:)
@Ghav2 жыл бұрын
This helped me when cutting the pizza for me and my six friends, thank you very much 😊
@MathVisualProofs2 жыл бұрын
😀
@McPilch Жыл бұрын
This needed to be done on IRL paper with the tools mentioned for added effect 😅
@MathVisualProofs Жыл бұрын
Some day maybe ;)
@RainShinotsu2 жыл бұрын
Very intriguing! I didn't know it was possible, but you made the problem and proof easy to understand.
@MathVisualProofs2 жыл бұрын
:) Thanks for the comment! Glad you enjoyed the video.
@orangesite7625 Жыл бұрын
Practically works for any number of divisions
@MathVisualProofs Жыл бұрын
Yep!
@xsquaredthemusician Жыл бұрын
Damn those shapes look so cool!
@MathVisualProofs Жыл бұрын
Right? 👍
@no_mnom2 жыл бұрын
This is really cool
@MathVisualProofs2 жыл бұрын
Thanks!
@thesquatchdoctor3356 Жыл бұрын
Extremely Satisfying.
@MathVisualProofs Жыл бұрын
:)
@MathrillSohamJoshi2 жыл бұрын
This is so cool !!
@MathVisualProofs2 жыл бұрын
😀
@jasonrubik2 жыл бұрын
Mind Blown ! Subscribed
@MathVisualProofs2 жыл бұрын
Thanks! Glad you liked this one.
@suicideistheanswer3692 жыл бұрын
Simple and beautiful.
@MathVisualProofs2 жыл бұрын
Thanks! :)
@vidiot55332 жыл бұрын
This demonstration is not limited to 7 sections. I wrote some functions in desmos and both plotted and calculated the areas of m sections where m is a positive integer, and it holds true for any value of m (odd, even, prime, nonprime, etc.) its an interesting bit of work but i don't think its worth saving as a unique file, so if you want to view it yourself, copy and paste the following code into desmos (make sure to limit m to integers by setting step to 1): m=1 a_{1}=\operatorname{round}\left(\frac{2\pi}{m^{2}}\left(\left[1...m ight]^{2}-\left[0...m-1 ight]^{2} ight),4 ight) a_{2}=\operatorname{round}\left(a_{1}\left[\operatorname{length}\left(a_{1} ight)...1 ight],4 ight) a_{3}=\operatorname{round}\left(\left(a_{1}+a_{2} ight),3 ight) A=\sum_{n=1}^{m}a_{3}\left[n ight] c=\frac{\left[1...m ight]}{m} c_{0}=\left[0...m-1 ight] c_{1}=\left[1...m ight] y=\sqrt{c^{2}-\left(x-c ight)^{2}} y=-\sqrt{c^{2}-\left(x+c-2 ight)^{2}} If you want to display some numerical data, copy/paste these three lines in and label them with the following information (desmos doesn't seem to support pasting label, color, or formatting information so I cant just paste it all in one nice block) \left(2c-\frac{1}{m},.05 ight) \left(2c-\frac{1}{m},-.05 ight) \left(2c-\frac{1}{m},-1 ight) {a1} {a2} {a3}
@MathVisualProofs2 жыл бұрын
:) nice work
@dodokgp2 жыл бұрын
Holy shit..this was a goldmine!
@MathVisualProofs2 жыл бұрын
😀
@RSLT2 жыл бұрын
Great Idea!
@MathVisualProofs2 жыл бұрын
Thanks! :)
@pyromen3212 жыл бұрын
This was an awesome video! Straight to the point and shows an amazingly simple solution to a complicated problem
@MathVisualProofs2 жыл бұрын
Thanks!
@baksoBoy2 жыл бұрын
woah that is super cool!
@MathVisualProofs2 жыл бұрын
👍 thanks!
@a_game_862 жыл бұрын
This is super interesting and informative, as well as being very intuitive, but I'm more confused about how other regular polygons can be constructed using classical tools but the heptagon cannot lol. Can I get an explanation as to why?
@MathVisualProofs2 жыл бұрын
This is actually quite a deep and challenging problem. You can find constructions of the polygons up to hexagon online. But proving that the heptagon cannot be constructed with classical tools is one of the famous impossibility problems and required a lot of relatively deep mathematics to prove.
@ratandmonkey29822 жыл бұрын
@@MathVisualProofs thank you. This would have been a nice bit to add at the beginning.
@bilbot.baggins90192 жыл бұрын
“bro just take a pizza slice like a normal person”
@MathVisualProofs2 жыл бұрын
😀
@Itoyokofan2 жыл бұрын
Would've been nice, if mathematical channels forgot the "straigt edge and compass" rule, and remembered that you can use a marked ruler (neusis) too, or a right angle ruler, with wich you can quite easily construct a heptagon.
@MathVisualProofs2 жыл бұрын
Sometimes I don’t use the classical requirement. I have two videos where I square the circle and so I have to use other tools :)
@Itoyokofan2 жыл бұрын
@@MathVisualProofs It's just seems ridiculous, that some DIY channels show how you can easily trisect an angle with a ruler, and some other geometrical shtiks up the woodworkers sleeves, but mathematical channels seems to avoid these themes altogether (I just happen to watch both). Would've been nice collaboration actually, if woodworker channel and mathematical channel made a collab, lol.
@MathVisualProofs2 жыл бұрын
@@Itoyokofan I’ll look around for someone maybe ;) as to the ruler and straightedge from math - it leads to famous impossibilities and the math that arose out of that is powerful and interesting so I guess that’s why math channels hold on to the classics tools
@SgtSupaman Жыл бұрын
I'm pretty sure if I could do a pentagon, I could do a heptagon. I can't do either, but you get my point.
@MathVisualProofs Жыл бұрын
But you’d be wrong :). Knowing how to do a pentagon gives no strategy for the heptagon. It’s impossible to construct a heptagon with classics tools.
@SgtSupaman Жыл бұрын
@@MathVisualProofs , heh, perhaps. Although, I wasn't trying to say the heptagon was derivative of the pentagon, just that, if I had the appropriate skill level to figure out one, I'd have the skill level to figure out the other.
@MathVisualProofs Жыл бұрын
@@SgtSupaman But even this isn't right :) You can obtain the skill to create the pentagon, but you will never obtain the skill to create a heptagon. And it takes a lot more work to prove that the heptagon is impossible :)
@SgtSupaman Жыл бұрын
@@MathVisualProofs , only impossible in theory. One can definitely draw a regular heptagon in a circle to a degree of certainty that is realistically covered by the width of the lines used. It's like trying to say it's impossible to ever travel a distance because you first have to travel half that distance, but you then have to first travel half that distance, and so on and so on. But, in reality, you quickly reach a point where the distances are so impossibly small they can't be halved.
@johnnytarponds9292 Жыл бұрын
Brilliant!
@MathVisualProofs Жыл бұрын
👍
@connorkearley77892 жыл бұрын
this is so cool thank you.
@MathVisualProofs2 жыл бұрын
Thanks for watching!
@GradientAscent_2 жыл бұрын
This is an awesome visual proof
@MathVisualProofs2 жыл бұрын
Thanks!
@at73882 жыл бұрын
Thanks for another great visual proof.
@MathVisualProofs2 жыл бұрын
Thanks for watching!
@-tsvk-2 жыл бұрын
Your initial examples of dividing the area of the circle into 2, 3, 4, 5 and 6 equally-sized pieces were a bit misleading, since those pieces were also equally-shaped, whereas in your solution for the division into 7 equally-sized pieces the pieces were not equally-shaped but different when compared to each other. So I was a bit confused first and felt a bit mislead about your solution, since I thought you were solving a different problem (= that the pieces should have to be equally-shaped). Is there a solution for the 7-division where the pieces have the same shape too?
@MathVisualProofs2 жыл бұрын
No intent to mislead. That is why I specifically used the phrase "of equal area" instead of equal size. The first examples are the natural thing to do... it is too bad that it fails for lots of values of n. So that's why I went somewhere else with n=7. Your question is excellent. I don't know of such a division... I would guess the answer is no, but I have no reason for that guess yet :) Thanks!
@anusface27602 жыл бұрын
POV: ur Voldemort and ur stuck on trying to figure out how to split ur soul into seven pieces for beginners
@ElectrifiedBacon2 жыл бұрын
my six friends gonna hate me next pizza party
@MathVisualProofs2 жыл бұрын
:)
@HeckaS Жыл бұрын
Beautiful
@MathVisualProofs Жыл бұрын
😃
@pujabaur49692 жыл бұрын
(1) In "Edison" it would be possible to create and play Loops in Any Order we like. Example. Loops=(2, 6, 8, 1) or (12, 1, 3, 6.10,) and
@MathVisualProofs Жыл бұрын
?
@markhughes7927 Жыл бұрын
Very good - very satisfying.
@MathVisualProofs Жыл бұрын
Thanks ! 😀
@bear_14102 жыл бұрын
that is so friggen cool lmao. thanks for making this video!
@MathVisualProofs2 жыл бұрын
Thanks for watching this video! :)
@jyggalag_2 жыл бұрын
That was brilliantly beautiful, sir!
@MathVisualProofs2 жыл бұрын
Thanks!!
@alesslg62812 жыл бұрын
Generalized version of the yin and yang
@jadenkhentagon3876 Жыл бұрын
Nice tutorial-5 Bro!
@MathVisualProofs Жыл бұрын
:) Thanks!
@rogerscottcathey Жыл бұрын
Trisection of an angle next!
@MathVisualProofs Жыл бұрын
I've got one in the works! It goes along with my squaring the circle videos: kzfaq.info/get/bejne/Zqpjfsx00tvRaWQ.html and kzfaq.info/get/bejne/lctkjNFm2q3enn0.html :)
@alexanderskladovski2 жыл бұрын
Finally, a way to cut pizza for 7-people party
@MathVisualProofs2 жыл бұрын
😀
@rayraythebrew28632 жыл бұрын
So it's the same concept of a ying-yang shape (where n=2 in that case), but expanding it further. Neat
@MathVisualProofs2 жыл бұрын
👍
@curiash Жыл бұрын
Subscribed
@MathVisualProofs Жыл бұрын
Thanks!
@rogerairborne Жыл бұрын
If you can't make a heptagon using a staight edge and compass, then use a protractor. 360/7=51.42.
@MathVisualProofs Жыл бұрын
Still only an approximation to 360/7.
@carly09et2 жыл бұрын
nice. A question how do you construct the regular pentagon with a straight edge and compass?
@MathVisualProofs2 жыл бұрын
Here’s one possible source: www.mathopenref.com/constinpentagon.html
@WilliamWizer Жыл бұрын
it's a nice trick but I would like to point that, although all seven areas have the same size, they aren't equal. they have different shape.
@MathVisualProofs Жыл бұрын
Yes. Most times I said "of equal area" but in one place I said "equal parts" (should have inserted the word "area" maybe).
@leecrawford6560 Жыл бұрын
ngl, I nearly lost it in a good way my mind was blown at the end then I said, "that was so cool"😀🤤
@MathVisualProofs Жыл бұрын
😀Thanks for sharing!
@DeathNight772 жыл бұрын
this video is great
@MathVisualProofs2 жыл бұрын
Thanks!
@tommyb66112 жыл бұрын
great stuff
@MathVisualProofs2 жыл бұрын
Thanks!
@lmarsh5407 Жыл бұрын
My approach qould be to just divide 360° into 7, and have each "pizza" slice have that angle. That is one simple way, although the video solution is cool too
@MathVisualProofs Жыл бұрын
Yes, this works but not with a straight edge and compass (one of the famous impossibilities is that you cannot draw 7 equally spaced points on the circle with classical tools).
@lmarsh5407 Жыл бұрын
@@MathVisualProofs I now believe I am ignorant (as in lacked knowledge) of what exactly using a straight edge and compass means. Afterlooking it up and understanding it further, I now understand the premise of the video lol. Thanks for the reply! it opened up my understanding more
@MathVisualProofs Жыл бұрын
@@lmarsh5407 No worries! It is a bit of a niche idea in mathematics :) Glad you checked it out, though! It leads to some cool mathematics.
@JusteazyGames Жыл бұрын
Pepsi Logo: *heavy breathing*
@MathVisualProofs Жыл бұрын
Haha
@remiwi23992 жыл бұрын
Simply beautiful
@MathVisualProofs2 жыл бұрын
Thank you! 😊
@charlesnelson51872 жыл бұрын
Nice!
@MathVisualProofs2 жыл бұрын
😀
@quantumgaming91802 жыл бұрын
Also, who discovered this gem of a proof?
@MathVisualProofs2 жыл бұрын
Not sure exactly I cited Roger Nelson’s book Icons of Math because that’s where I learned it.
@user-ry4ip9ps9x Жыл бұрын
Wait, but I still don't undestand why a regular heptagon can't be constructed using a straight edge and compass? Where the areas of those 7 sectors not equal?
@MathVisualProofs Жыл бұрын
It turns out you just can't do that construction with straightedge and compass. You can divide the circle into seven equal areas with the regular heptagon, and there are ways to construct the regular heptagon; just can't do it with the two classical tools.
@stanleydenning Жыл бұрын
I'm sorry. But, you fell short on this exercise in math and geometry. Take a closer look. It's fascinating.
@MathVisualProofs Жыл бұрын
Can you explain or clarify?
@zechariahcaraballo87652 жыл бұрын
cant wait to do this to a pizza
@MathVisualProofs2 жыл бұрын
😀
@derfunkhaus Жыл бұрын
Could you approach the problem by starting with the hexagon method, giving you 6 equal pie slices, and then creating a small circle in the middle which is equal to 1/7 of the area of the whole circle? i.e. Each of the six pie slices gives up a little of its tip to contribute to the inner circle.
@MathVisualProofs Жыл бұрын
That should probably work too! Cool idea.
@Fungo4 Жыл бұрын
Wouldn't that require you to measure a diameter of √7?
@MathVisualProofs Жыл бұрын
@@Fungo4 yes. But root 7 is constructible too :)
@derfunkhaus Жыл бұрын
@@Fungo4 Apparently -- by which I mean, "according to my search of the subject on google" -- the square root of 7 is constructable using a ruler and compass. For example see the Wikipedia article on "Dynamic rectangle." I guess the way to go about it would be to create the line segment of root 7 length first, using the dynamic rectangle method mentioned above, and then use that as the radius of your larger circle. This would have an area of 7pi. Then use the first step of the dynamic rectangle process, which was a unit square, and use that to create the inner circle with radius 1. This smaller circle has a radius of pi, or 1/7 of the larger circle. The ring outside this smaller circle has area 6pi. Finally, divide the larger circle into 6 equal arcs each of which has an area of pi. Admittedly, this approach is pedestrian in comparison to the one in the video, and the shapes are not as beautiful or interesting. EDIT: also, using the dynamic rectangle method you could draw a new circle with each new radius (1, root 2, root 3, and so on) and each ring would have area 1pi.
@Fungo4 Жыл бұрын
@@derfunkhaus Wow, that's so simple I can't believe I never thought of it!
@jan_Masewin2 жыл бұрын
Can’t wait to do thos with my next pizza order :D
@MathVisualProofs2 жыл бұрын
Want to see this done :)
@bignicebear24282 жыл бұрын
Next time I get a pizza I will order it cut just like that.
@MathVisualProofs2 жыл бұрын
I’d like to see it!
@mehblahwhatever2 жыл бұрын
Time to cut my pizza like an absolute madman
@MathVisualProofs2 жыл бұрын
I would love to see a pizza divided this way. Great idea!
@-private82142 жыл бұрын
now i just gotta wait for an opportunity to show that off, the problem ist that german schools couldn't care less about problem solving
@huhneat10762 жыл бұрын
Yin, yang, and uh... yong, yum, yanney, yan, and yern.
@MathVisualProofs2 жыл бұрын
Hah! :)
@BeefinOut2 жыл бұрын
Really cool proof, but it relies on a lot of assumptions. I'm only vaguely familiar with compass and straightedge problems, so when you say things like "you can construct 3- to 6-sided shapes but not 7-sided" or "go ahead and divide the diameter into 7 equal parts," I end up needing to take your word for it. Not sure how complicated it would have been to fully illustrate the context and process of this proof, maybe that's outside the scope of the video, but I would have liked to have it
@MathVisualProofs2 жыл бұрын
Thanks! Yes, those would take some time and would have taken away from the point of the video. Plus there are lots of places showing constructions of the regular n-gons, so I didn't necessarily want to hit those again.
@BeefinOut2 жыл бұрын
@@MathVisualProofs makes sense. I think the reason you're getting some comments like mine is because this video got picked up by the algorithm, so it has a broader audience with less subject matter familiarity than your other videos.
@MathVisualProofs2 жыл бұрын
@@BeefinOut You're probably right :) Funny thing about the algorithm is that most of my videos are broader in the background knowledge required - but it liked this one for some reason :) Thanks!
@anadiacostadeoliveira42 ай бұрын
Wow! If it was a logo, I'll be happy!
@tomasbernardo59722 жыл бұрын
Did you use manim to do this animation?
@MathVisualProofs2 жыл бұрын
Yes. Still using manimgl
@stvp689 ай бұрын
I have long wondered about hubcaps with 7 spokes
@maradupras72782 жыл бұрын
gonna order a pizza cut like this
@MathVisualProofs2 жыл бұрын
definitely want to see it!
@SuperYoonHo2 жыл бұрын
Nice sir
@MathVisualProofs2 жыл бұрын
Thanks!
@jaafars.mahdawi6911 Жыл бұрын
Wow!
@quinnculver Жыл бұрын
Bravo!
@MathVisualProofs Жыл бұрын
Thanks :)
@Shmookcakes2 жыл бұрын
Is there any modern import to proofs or operations limited to classical tools? Or is it simply a limitation for its own sake (fun)?
@MathVisualProofs2 жыл бұрын
There is a lot of modern mathematics that was developed to prove that certain things are impossible. So the limitation is a nod to that I think. The idea of proving the impossibility of certain tasks really was a fascinating change in thinking.
@gazbot9000 Жыл бұрын
But the pie crust allocation is far from equal which could lead to negative outcomes
@MathVisualProofs Жыл бұрын
Good point. :)
@caymansharp6232 жыл бұрын
I wonder if this is how those swirley marbles are made assuming this works with a three dimensional sphere
@MathVisualProofs2 жыл бұрын
Interesting thought! I have no clue about that :)
@1ab1 Жыл бұрын
Interesting. Now i wonder if there's a way so that 7 dwarfs can also simultaneously share the same amount of crust🤔
@MathVisualProofs Жыл бұрын
👍
@LeoStaley2 жыл бұрын
Hang on, how do you divide up the diameter of the semicircle into 7 equal parts? Edit, I don't know, but I rid realize it's easy to just make a line segment and repeat it 7 times. Find the mind point of the middle one, make a circle from that.
@MathVisualProofs2 жыл бұрын
Far from obvious. Here is a link that shows how to cut any line into n pieces for n a positive integer : www.mathopenref.com/constdividesegment.html
@VoxelMusic2 жыл бұрын
This reminds me of a puzzle.
@MathVisualProofs2 жыл бұрын
With more slices it could be a cool one to have :)
@VoxelMusic2 жыл бұрын
LS149 Marble Thirds
@Yubin_Lee_Doramelin2 жыл бұрын
I found out this idea was extended from constructing Yin-Yang symbol, especially the one used in South Korean flag "Taegeukgi (태극기, 🇰🇷)"! How amazing it is...!
@MathVisualProofs2 жыл бұрын
Very cool!
@FrumiousBandersnatch42 Жыл бұрын
But WHY can't we construct a regular heptagon using a straight edge and compass? Can you prove it can't be done?
@MathVisualProofs Жыл бұрын
It is provable. But not in my format
@Blade_of_Tomoe2 жыл бұрын
Lovely.
@MathVisualProofs2 жыл бұрын
😀
@willytor78992 жыл бұрын
Gonna start cutting pizzas like this
@MathVisualProofs2 жыл бұрын
Want to see it :)
@CathodeRayKobold2 жыл бұрын
All hail the Math Pepsi.
@CathodeRayKobold2 жыл бұрын
I could also say this would have made a SICK sports equipment logo from the 70s-80s.