Rational curvature, winding and turning | Algebraic Topology | NJ Wildberger

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  • čas přidán 27. 07. 2024

Komentáře • 14

  • @Myrslokstok
    @Myrslokstok Před 12 lety +1

    The Prof is very easy to listen to and it gets better and better.

  • @JasonQuackenbushonGoogle
    @JasonQuackenbushonGoogle Před 2 lety +1

    I'm so glad i found this video. it clarified a lot of the things id been trying to figure out about circular functions related to rational trig

  • @brendawilliams8062
    @brendawilliams8062 Před 3 lety +1

    Very nice. Thx. Dr. Wildberger.

  • @ReeshaEducation
    @ReeshaEducation Před 3 lety +1

    Thank you so much Sir.

  • @vice-sama3015
    @vice-sama3015 Před 5 lety

    Sure buddy. Sure. Very revolutionary of you to think in such a novel way. Can we get a fields medal over here. That aside, nice series of lectures

  • @TheAbcdane1
    @TheAbcdane1 Před 12 lety +2

    you're great.

  • @hellenakinyi7942
    @hellenakinyi7942 Před rokem +1

    Video Content
    00:00 Introduction
    01:20 Angle(Spread Rational Trigonometry- Overview
    02:50 Q. How to describe the amount of turning?
    06:40 Turn of the basics unit
    10:00 Turn angles
    15:54 Quadrilateral Turn angles
    17:48 n-gon computation
    19:48 Convex polygon
    22:50 General n-gon
    25:00 Alternate approach of the T angle
    28:00 Total curvature of Convex Polygon
    30:45 Winding numbers of a curve
    34:48 The turning on different points of the curve
    41:10 Turning number of a smooth curve

  • @njwildberger
    @njwildberger  Před 11 lety

    If you must have a ''unit'', might it be ``turn''? So e.g. we go 1/4 turn when we go from horizontal to vertical etc.
    But I think it good to have a discussion about whether a unit is actually required here, since the rational turn angle is a ratio of two similar things. Is there such a thing as a dimensionless unit??

  • @njwildberger
    @njwildberger  Před 12 lety

    No, in that case there is no contribution. You can see that by moving the curve just a little, so that north is no reached, or north is passed through in one direction and then immediately after that in the other direction.

  • @njwildberger
    @njwildberger  Před 12 lety

    Admittedly the two concepts are pretty close, but often we want to think of a turn angle as a measurement, ie a number.

    • @martinworrell1167
      @martinworrell1167 Před 4 lety

      Do you have a topological proof of the Morley's Triangle? The trisectors seem to be rational tangles, so maybe there's an elegant proof :)

  • @njwildberger
    @njwildberger  Před 11 lety

    The usual way circular functions like sin x are ``defined'' is to treat x as a ``real number'', without any dimensions.

  • @ac-dp3jk
    @ac-dp3jk Před 6 lety +1

    Sir, thank you very much for this great lecture. I have a question: Using tangles, do the complex numbers need re-scaling too ? For example, what happens to formulas like e^(i\pi)=-1 ?

    • @millerfour2071
      @millerfour2071 Před 5 lety

      Just replace \theta with 2\pi\tau. As mention by Albert Steiner below. In order to obtain the usual derivative relationships between cos and sin, hence to get their Taylor series and obtain Euler's formula, it is necessary to use the conventional definition so that differential arc length is rd\theta. So in that respect, the tangle is not very useful.