Integral formulas for area, volume (disk method), arc length, & surface area

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  • เผยแพร่เมื่อ 28 ก.ย. 2024

ความคิดเห็น • 52

  • @bprpcalculusbasics
    @bprpcalculusbasics  4 หลายเดือนก่อน +5

    Examples of
    disc method for the volume of the solid of revolution: th-cam.com/video/uiEEEx7mPHg/w-d-xo.htmlsi=Znn3zTxHzseDBjQP
    how to use these formulas: th-cam.com/video/hM6Zq4f68yU/w-d-xo.html

  • @perekman3570
    @perekman3570 4 หลายเดือนก่อน +47

    This is so brilliant. So many students could learn from this, instead of just blindly applying a formula, instead understand the how's and why's and derive the formulas themselves when needed.

  • @Ruija27
    @Ruija27 4 หลายเดือนก่อน +4

    Hey, this is really great! I saw that the ordinary math basics channel is really quite basic at times, not dismissing even basic operations like addition or multiplication as super obvious. this calculus basics channel doesn't seem to have as much of the same true basics, on integrals and derivatives and such.
    Hopefully there will be more of the "you did a few years of calculus in high school but forgot all about it" types of primer videos over time!

  • @thegamer7537
    @thegamer7537 4 หลายเดือนก่อน +5

    Thank you so much man. I have consumed hours of your content, and it has taught me so much math, and inspired me to get even better at math and learn advanced concepts; which has been made so much easier through your content. Thank you so much for preparing me for the difficult classes in high school, even though I am in the seventh grade, and I wish you the best and only the best.

  • @cyrusyeung8096
    @cyrusyeung8096 4 หลายเดือนก่อน +12

    Proof of formula at 17:44
    We know area of sector is ½r²θ,
    and circular arc length is rθ,
    where r is radius and θ is angle of sector.
    Suppose we let r be the smaller radius, and R be the larger radius
    Then,
    l = middle radius × θ = ½(R + r)θ
    area of the "strip"
    = ½R²θ - ½r²θ
    = ½(R² - r²)θ
    = [½(R + r)θ] × (R - r)
    = lw

    • @salmonsushi47
      @salmonsushi47 2 หลายเดือนก่อน

      not all the cut out strips for different functions would be of that shape right? so isnt it better to go with a general limit intuition that as we reduce the width of strip cut outs approximate rectangle more and more?

  • @hanswurst3394
    @hanswurst3394 4 หลายเดือนก่อน +18

    Its phenomenal how good you explain this formulars.

  • @abacaabaca8131
    @abacaabaca8131 4 หลายเดือนก่อน +1

    One of the application of integration in calculus is to paint an area of an object regardless of the shape.
    If you try to do this in code, you can try iterate over a set of parameter to a function, and draw a single line every time.
    This is what i tried to do in my app.later i will try to fix it by using unit testing.

  • @ToeNailMuncher111
    @ToeNailMuncher111 4 หลายเดือนก่อน +2

    Worlds best prof.

  • @saravanarajeswaran2626
    @saravanarajeswaran2626 4 หลายเดือนก่อน +3

    the last shape ,which you called a part of a cone ,in india we studied that as frustum of a cone with c.s.a pi.l(r1 + r2),hey just telling

  • @krisbrandenberger544
    @krisbrandenberger544 หลายเดือนก่อน

    Hey, blackpenredpen! The results for rotating the curve about the y-axis will have an xdx and a g(y)dy, just by playing the same game with rotation about the x-axis.

  • @tobybartels8426
    @tobybartels8426 4 หลายเดือนก่อน +2

    ds for arclength, dS for surface area, so you don't mix them up. (I've also seen dσ for surface area so that dS can be used for the vector version.) But really, ds for arclength is a very strange letter to use!

    • @carultch
      @carultch 4 หลายเดือนก่อน

      Also, draw a cursive s to tell it apart from a 5, and to tell lowercase s apart from capital S.

  • @RadhakrishnanNair-zn8vh
    @RadhakrishnanNair-zn8vh 4 หลายเดือนก่อน

    Simply beautiful,Sir...Thank You very much...

  • @thexoxob9448
    @thexoxob9448 4 หลายเดือนก่อน

    About the S.A. part don't you jave to add the areas of the circles?

  • @sinekavi
    @sinekavi 4 หลายเดือนก่อน +1

    Integral of ((1-x^7)^(1/4) - (1-x^4)^(1/7)) can you please solve this integral BPRP?

    • @cyrusyeung8096
      @cyrusyeung8096 4 หลายเดือนก่อน

      Wolfram Alpha says you would need the hypergeometric function, so it is non-elementary.

    • @bprpcalculusbasics
      @bprpcalculusbasics  4 หลายเดือนก่อน +1

      I think you wanted it from 0 to 1?

    • @sinekavi
      @sinekavi 4 หลายเดือนก่อน

      @@bprpcalculusbasics Yes from 0 to 1

    • @josip.harasic
      @josip.harasic 4 หลายเดือนก่อน

      =0

  • @thundercraft0496
    @thundercraft0496 4 หลายเดือนก่อน +1

    There's a lot of abuse of notation
    But i still like it

    • @bprpcalculusbasics
      @bprpcalculusbasics  4 หลายเดือนก่อน +1

      That’s why I didn’t say I was proving these formula in the video haha.

  • @AlRoderick
    @AlRoderick 4 หลายเดือนก่อน +6

    Saw you hesitate a bit as to whether to spell the word dis(c/k) with a c or a k. Strong disagreement between the manufacturers of floppies, the manufacturers of CDs, and spinal surgeons.

    • @bprpcalculusbasics
      @bprpcalculusbasics  4 หลายเดือนก่อน +4

      Good catch! 😆

    • @lostwizard
      @lostwizard 4 หลายเดือนก่อน

      General rule of thumb: use "disc" unless it is referring to a rotational magnetic storage medium or something using the same form factor. (Floppy disk, hard disk (even solid state), but compact disc, spinning disc, the disc of the sun, etc.)

  • @Misteribel
    @Misteribel 4 หลายเดือนก่อน +10

    Love how you use integrals to calculate volume and area. In my secondary school years, it was taught that integrals were jnvented for this case, and the teacher used all this in several sessions to explain the why and what of integrals.

    • @thexoxob9448
      @thexoxob9448 2 หลายเดือนก่อน

      Integrals mean the sum as dx gets really small

  • @thewok3576
    @thewok3576 4 หลายเดือนก่อน +3

    You can think that "((dy)/(dx))^2" is the same thing as "(f'(x))^2". Great video though!

    • @thewok3576
      @thewok3576 4 หลายเดือนก่อน

      You can also integrate the circumference of a disc in order to get the surface area of any volumetric object.

    • @thewok3576
      @thewok3576 4 หลายเดือนก่อน

      I don't think dL is necessary, dx works as well (if I'm not mistaken).

  • @aissaaftis
    @aissaaftis 4 หลายเดือนก่อน +4

    Hello

  • @_-alessandro-_3027
    @_-alessandro-_3027 4 หลายเดือนก่อน +4

    Hi, thanks for the video! how can we formally proof these formulas? Because this is only a geometric rappresentation of the situation

    • @kristopherwilson506
      @kristopherwilson506 4 หลายเดือนก่อน +1

      A real analysis class :) formally showing these can be complicated. Since integration is a limiting process, we know that the distance between what we want-in this case, the Riemann sum and the value of the integral-needs to be less than some arbitrarily small value epsilon.

  • @khurramshahzad-ds1oj
    @khurramshahzad-ds1oj 4 หลายเดือนก่อน +1

    Excellent

  • @leonardobarrera2816
    @leonardobarrera2816 4 หลายเดือนก่อน +2

    Coooool

  • @atomicblack4862
    @atomicblack4862 4 หลายเดือนก่อน +1

    How to proof that the definite integral is F(b) - F(a) ?

  • @nonentity168
    @nonentity168 4 หลายเดือนก่อน +1

    I love how dedicated you are in making educational content that makes it accessible to the general public. Long may it lasts ⭐⭐⭐⭐⭐

  • @AlbertTheGamer-gk7sn
    @AlbertTheGamer-gk7sn 4 หลายเดือนก่อน

    Also, these all come from double/triple integrals:
    A = ∬dA = ∬dydx= ∬rdrdθ = ∫ydx = 0.5∫r^2dθ
    V = ∭dV = ∭dzdydx = ∭rdzdrdθ = ∬zdA = ∬zdydx= ∬zrdrdθ = ∫Adx = ∭rdrdθdx = 0.5∬r^2dθdx = π∫r^2dx
    L = ∮u ∙ dr = ∫ds = ∫√(1+y'^2)dx = ∫√(x'^2+y'^2)dt = ∫√(r^2+r'^2)dθ
    SA = ∯u ∙ dS = ∬dS = ∬√(1+z_x^2+z_y^2)dydx = = ∫2πρds

  • @5Stars49
    @5Stars49 4 หลายเดือนก่อน +2

    Lovely

  • @komalshah1535
    @komalshah1535 4 หลายเดือนก่อน +2

    Outstanding!

  • @jomariraphaellmangahas1991
    @jomariraphaellmangahas1991 3 หลายเดือนก่อน

    I think it is good to publish a book that contains all the formulas

  • @forcelifeforce
    @forcelifeforce 4 หลายเดือนก่อน +1

    @ *bprp calculus basics* -- It would be good for the audience for you to demonstrate the same example across each of area, volume, arc length, and surface area to make it more concrete.

    • @bprpcalculusbasics
      @bprpcalculusbasics  4 หลายเดือนก่อน

      Yes. I have the example videos in the pinned comment.

  • @mohannad_139
    @mohannad_139 4 หลายเดือนก่อน +1

    Can you please do one for calc 3 integrals? The double integral, line integral & surface integral

    • @bprpcalculusbasics
      @bprpcalculusbasics  4 หลายเดือนก่อน +1

      Unfortunately I am not too familiar with those topics since I haven’t taught it, but hopefully one day!

  • @blansimon7227
    @blansimon7227 4 หลายเดือนก่อน

    Hi, my math teacher could not solve this, if someone could help me please xd
    5^x+3^x=7

    • @sinekavi
      @sinekavi 4 หลายเดือนก่อน +1

      Take natural log on both sides......
      ln5^x + ln3^x=ln7
      xln5 + xln3=ln7
      x(ln5+ln3)=ln7
      x=ln7/(ln5+ln3) I am not sure whether I am correct......
      So please check with your teacher again whether my answer is correct

    • @blansimon7227
      @blansimon7227 4 หลายเดือนก่อน +2

      ​@@sinekaviWhen we take natural logarithm on both sides the whole expression is caged, so in the first step should be:
      Ln(5^x+3^x)=Ln7
      So it's not correct, but thanks for trying anyway!