A log trig integral with a beautiful result
Exactly what the title says...
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Пікірлер: 33
Use properties of definite integrals, replace θ by (π/2 - θ) and add both I. Pretty straight forward and easier haha.
@maths_505
9 күн бұрын
Oh yeah 😂 but this is more fun
@user-lu6yg3vk9z
8 күн бұрын
@@maths_505why didn’t u use kings property?
@famillemagnan1313
8 күн бұрын
Much easier indeed!
@manjugangwar7245
7 күн бұрын
I used the same
Love when he writes π as a и with - on top of it
@vladthemagnificent9052
8 күн бұрын
ln, sin, and tan also looks like lu siu and tau
Replacing theta with x, the curve is symmetric with respect to the segment from (0,2) to (pi/2,0), so the area of that triangle is pi/2.
i encountered this integral in school: integral from 0 to 1 of xe^x, i obviously solved it using integration by parts and it resulted in 1 but i tried to generalize it using a parameter alpha in the exponent of x so i got the integral of x^alpha*e^x but i'm not smart enough to solve it and i would love to see it in one of the next videos. also i love watching your videos, especially at night since they're so relaxing and they help me falling asleep. great work! keep it up
Ohh man just replace θ by (π/2 - θ) And then add both. You'll get, 2 I = ∫ { ln(tan²θ) / ln(tanθ) }dθ = ∫ 2 dθ = π I = π/2
This is gorgeous, thank you very much.
Some people are somehow not happy with you not using that easy 2 liner solution. But (at least to me), this one was way more fun. I think sometimes, the way matters more than the result. And Ik it's better to have a simple solution, but still sometimes the complex one is the one which actually seems interesting and more fun. So thanks!
@maths_505
9 күн бұрын
Thanks for getting it homie
@SussySusan-lf6fk
7 күн бұрын
Yep 😊
A wild integral representation of pie.
Basically this is saying the magnitude of sin2theta relative to tantheta along the first quadrant changes by a rate of pi/2 (up to a constant).
The integral reduces to int(1)dx from 0 to pi/2 using King, Log, and Trig properties without substitution.
Here's the solution in 3-4 line -- I= ∫ [ (stuff) -1+1]d∅ now take lcm With -1 U will find inside logarithms upstairs ln(sin2∅) Downstairs ln(tab∅) You have listen about The KINGS rule apply to the above integral and you will find the integral collapse 0 , ∫d∅ from π/2to 0 = π/2 ans
Greetings Kamal, i also forget how to talk from time to time 😂😂
At the point where you expand by e^x/2 (9:08), the integrand readily becomes sech(x/2) when multiplied by 2. 1/2Integrate[Sech[x/2], x,-infy,infy] Nevertheless, the z-substitution afterward was nifty.
It's all making sense now, the Black speech of Mordor, sounded very scary when I was a child, cause it was all maths.😁 I even got some hints for this to be true at school, when writting a test, and I looked to my neighbours test for a second, the teacher gave me a nasty look, and said "I see yooouuu."😅
Another dope integral representation of π
Using the change of variable u=pi/2 - thêta, and addint it to the initial integral leads to the results much faster. (A bit frustrated for you not using it)
Nice!
@maths_505
9 күн бұрын
Thanks mate
Hi, "ok, cool" : 1:11 , 1:56 , 2:29 , 3:46 , "Terribly sorry about that" : 4:55 , 6:31 .
i didnt understand the part where u say as x is an odd function but the others are even functions ,due to even f(x) the integral converges to zero from negative to positive infinity
Mi sembra troppo semplice 2I=Int(2)dx(0...π/2)=π..I=π/2
Is there any textbook for these kimd of question
Which country are you from? Your are videos are so good
@maths_505
9 күн бұрын
I'm from Pakistan
No beta function??, are you okay??
@trelosyiaellinika
8 күн бұрын
😂