An outrageous journey of integration: int 0 to π/4 arctan(cot^2(x))

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  • เผยแพร่เมื่อ 5 ม.ค. 2025

ความคิดเห็น • 35

  • @ΓκεριΚουτα
    @ΓκεριΚουτα ปีที่แล้ว +15

    I really loved integrals at high school and University but right now, due to engineering degree, i have overspecialised myself in matrixes and recursive algorithms. Due to your videos my passion has sparked once again!! Do you have any theory pdfs? You seem to have a talent in explaining things!!

    • @maths_505
      @maths_505  ปีที่แล้ว +14

      I'm gonna start my complex analysis course in September. Everyone will have access to pdfs and homework help for the questions I assign.

    • @anasharere
      @anasharere ปีที่แล้ว +6

      @@maths_505🎉🎉🎉🎉lets gooo

  • @manstuckinabox3679
    @manstuckinabox3679 ปีที่แล้ว +2

    these integrals are becoming more insane by the day... I love it!

  • @xizar0rg
    @xizar0rg ปีที่แล้ว +2

    The titling on this video is excellent. Thank you for the clear labeling.

  • @maxvangulik1988
    @maxvangulik1988 11 หลายเดือนก่อน

    that can be simplified further. I recognize 3+2sqrt(2) as (1+sqrt(2))^2, so the final answer can be written as (pi^2-2ln^2(1+sqrt(2)))/8
    (the 2 from the exponent gets taken out twice because it's a ln^2)

  • @kim2key
    @kim2key ปีที่แล้ว

    how do you make the step on 4:25. The first integral is logic but why can you convert it to that integral from 0 to 1

    • @maths_505
      @maths_505  ปีที่แล้ว

      I changed the variable to ut

  • @mrgold4678
    @mrgold4678 ปีที่แล้ว +3

    I think it becomes more beautiful if you write this as
    I = pi^2/8 - ln^2 (1 + sqrt(2))^2 / 16 = pi^2/8 - ln^2 (1+sqrt(2)) / 4

  • @Risu0chan
    @Risu0chan ปีที่แล้ว

    Where does that sum of fractions @5:36 come from?

    • @maths_505
      @maths_505  ปีที่แล้ว

      It's a partial fraction decomposition

  • @MrWael1970
    @MrWael1970 ปีที่แล้ว

    Thank you for your effort.

  • @Maths_3.1415
    @Maths_3.1415 ปีที่แล้ว +4

    You should make some videos with chat gpt

  • @romanroman6817
    @romanroman6817 ปีที่แล้ว

    Great Integral

  • @jophua4532
    @jophua4532 ปีที่แล้ว

    can i ask where you find these integrals?

    • @maths_505
      @maths_505  ปีที่แล้ว +1

      This one's from a subscriber

    • @jophua4532
      @jophua4532 ปีที่แล้ว

      @@maths_505thanks tryna get better 💪

  • @yoav613
    @yoav613 ปีที่แล้ว

    👏👏👏👏👏👏

  • @BadlyOrganisedGenius
    @BadlyOrganisedGenius ปีที่แล้ว

    3+2sqrt(2) = (1+sqrt(2))^2
    so [ln(3+2sqrt(2))]^2 = [2*ln(1+sqrt(2))]^2 = 4*[ln(1+sqrt(2))]^2 = 4*arsinh(1)^2

  • @orionspur
    @orionspur ปีที่แล้ว

    OMG... Wolfram Alpha computes this result for the indefinite integral:
    integral arctan(cot^2(x)) dx
    = x tan^(-1)(cot^2(x)) + 1/4 (2 cos^(-1)(-sqrt(2)) tan^(-1)((-1 + sqrt(2)) cot(x + π/4)) - 2 cos^(-1)(sqrt(2)) tan^(-1)((1 + sqrt(2)) cot(x + π/4)) - π tan^(-1)(1 - sqrt(2) tan(x)) - π tan^(-1)(sqrt(2) tan(x) + 1) - (π - 4 x) tan^(-1)((-1 + sqrt(2)) tan(x + π/4)) + (π - 4 x) tan^(-1)((1 + sqrt(2)) tan(x + π/4)) + i (cos^(-1)(sqrt(2)) - 2 tan^(-1)((1 + sqrt(2)) cot(x + π/4))) log((sqrt(2) (1 - i cot(x + π/4)))/(i cot(x + π/4) + sqrt(2) - 1)) - i (2 tan^(-1)((-1 + sqrt(2)) cot(x + π/4)) + cos^(-1)(-sqrt(2))) log((sqrt(2) (i cot(x + π/4) + 1))/(i cot(x + π/4) + sqrt(2) + 1)) + i (2 tan^(-1)((1 + sqrt(2)) cot(x + π/4)) + cos^(-1)(sqrt(2))) log(-(i (-2 + sqrt(2)) (cot(x + π/4) - i))/(i cot(x + π/4) + sqrt(2) - 1)) - i (cos^(-1)(-sqrt(2)) - 2 tan^(-1)((-1 + sqrt(2)) cot(x + π/4))) log((i (2 + sqrt(2)) (cot(x + π/4) + i))/(i cot(x + π/4) + sqrt(2) + 1)) - i (2 tan^(-1)((1 + sqrt(2)) cot(x + π/4)) + 2 tan^(-1)((-1 + sqrt(2)) tan(x + π/4)) + cos^(-1)(sqrt(2))) log(((1/2 + i/2) e^(-i x))/sqrt(sqrt(2) - sin(2 x))) - i (-2 tan^(-1)((1 + sqrt(2)) cot(x + π/4)) - 2 tan^(-1)((-1 + sqrt(2)) tan(x + π/4)) + cos^(-1)(sqrt(2))) log(((1/2 - i/2) e^(i x))/sqrt(sqrt(2) - sin(2 x))) + i (2 tan^(-1)((-1 + sqrt(2)) cot(x + π/4)) + 2 tan^(-1)((1 + sqrt(2)) tan(x + π/4)) + cos^(-1)(-sqrt(2))) log(-((1/2 - i/2) e^(-i x))/sqrt(sin(2 x) + sqrt(2))) + i (-2 tan^(-1)((-1 + sqrt(2)) cot(x + π/4)) - 2 tan^(-1)((1 + sqrt(2)) tan(x + π/4)) + cos^(-1)(-sqrt(2))) log(((1/2 + i/2) e^(i x))/sqrt(sin(2 x) + sqrt(2))) - Li_2(-((-1 + sqrt(2)) (-i cot(x + π/4) + sqrt(2) - 1))/(i cot(x + π/4) + sqrt(2) - 1)) + Li_2(-((1 + sqrt(2)) (-i cot(x + π/4) + sqrt(2) - 1))/(i cot(x + π/4) + sqrt(2) - 1)) + Li_2(((-1 + sqrt(2)) (-i cot(x + π/4) + sqrt(2) + 1))/(i cot(x + π/4) + sqrt(2) + 1)) - Li_2(((1 + sqrt(2)) (-i cot(x + π/4) + sqrt(2) + 1))/(i cot(x + π/4) + sqrt(2) + 1))) + constant

    • @Maths_3.1415
      @Maths_3.1415 ปีที่แล้ว +1

      Professor:-the paper comprises of only 1 integral worth 100 pts
      Integral :-

  • @giuseppemalaguti435
    @giuseppemalaguti435 ปีที่แล้ว

    I=3(pi/4)^2-[1-1/3(1-1/3+1/5)+1/5(1-1/3+1/5-1/7+1/9)-1/7(1-1/3+1/5-1/7+1/9-1/11+1/13)....-]...questa è la soluzione corretta 1,03...

  • @zunaidparker
    @zunaidparker ปีที่แล้ว +1

    Feels like you jumped a lot of in between steps in the first 4 mins worth of manipulations. A bit too quick to follow vs doing the step by step substitutions methodically. Very cool integral nonetheless!

    • @maths_505
      @maths_505  ปีที่แล้ว +1

      HE'S ALIVE!!!
      HE'S ALIVVVVVVVVVEEEEEEEEE!!!!

    • @maths_505
      @maths_505  ปีที่แล้ว +1

      Thankfully it was fast enough to hear from you 😂?
      How you been mate?

    • @zunaidparker
      @zunaidparker ปีที่แล้ว

      @@maths_505 alive and well! I'm literally always around, I just don't comment every video. But the like goes up on every one even before I watch it!
      How about some multi-variable calculus? Solids of revolution, Greene and Stokes' Theorem etc.?

    • @maths_505
      @maths_505  ปีที่แล้ว +1

      I like the complex versions of them better. The complex analysis series starts in the first week of September.

    • @maths_505
      @maths_505  ปีที่แล้ว +1

      And thank you so much G

  • @Maths_3.1415
    @Maths_3.1415 ปีที่แล้ว +2

    First

  • @bartekabuz855
    @bartekabuz855 ปีที่แล้ว

    Come back to the dark side pls lord Vader

    • @maths_505
      @maths_505  ปีที่แล้ว +2

      Vader has been gone for too long indeed....

    • @bartekabuz855
      @bartekabuz855 ปีที่แล้ว

      @@maths_505 I meant the thumbnail lmao. Vader is dead since 80s tho

    • @maths_505
      @maths_505  ปีที่แล้ว

      @@bartekabuz855 oh so I don't have to use the infinity stones to snap him back?
      Ah well....I'll save em for another occasion.