Can the value of pi be found through integration?

  • Context: Undergrad 
  • Thread starter Thread starter AndersHermansson
  • Start date Start date
  • Tags Tags
    Integral
Click For Summary

Discussion Overview

The discussion centers around the possibility of finding the value of pi through the evaluation of a specific integral, namely the integral of the square root of (1 - x²) from 0 to 1. Participants explore methods of integration, including trigonometric substitution, and discuss the relationship between the integral and the geometry of a semicircle.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant questions whether an exact solution for the integral ∫√(1-x²)dx from 0 to 1 can be found, suggesting that it relates to the value of pi.
  • Another participant asserts that the integral represents a quarter circle and claims that the result is 1/4 pi, indicating a geometric interpretation.
  • A third participant proposes using trigonometric substitution (x = sin(θ)) to evaluate the integral, suggesting that this method will yield pi/4.
  • One participant expresses confusion regarding the variable x and the nature of the integral, questioning whether x is a complex variable.
  • Another participant implies that the integral may be simpler than it appears, although this is not elaborated upon.

Areas of Agreement / Disagreement

Participants present multiple competing views on the evaluation of the integral and its relation to pi. There is no consensus on the exact interpretation or method to be used.

Contextual Notes

Some participants reference trigonometric substitution as a method for evaluating the integral, but the discussion does not resolve the specifics of this approach or its implications for the integral's value.

Who May Find This Useful

This discussion may be of interest to those exploring calculus, integration techniques, and the geometric interpretations of integrals related to pi.

AndersHermansson
Messages
61
Reaction score
0
Is it possible to find an exact solution for this integral?

∫√(1-x*x)dx from 0 to 1

Is it possible to differentiate a root expression?

I found that:
pi = 4 * ∫√(1-x*x)dx from 0 to 1
 
Physics news on Phys.org
the equation is for a semicircle of radius 1 from 0 to 1 you get a quarter circle and 1/4 pi *r^2=1/4pi

1/4pi is the answer
you could also evaluate the integral using a trig subsitution

you already found the answer if you divide both sides of the equation by 4 in your solution you also get the answer
 
Last edited:
for the trig sub

x=sin(θ)
dx=cos(θ)dθ
substitute into original integral simpligy trig expresion and switch limits of integration (evaluate interms of theta) and you will get &pi/4

if you haven't learned trig subs check it out in your calc book it not a very hard topic.
 
what is x*? is x a complex variable? i don t quite understand your integral
 
Probably because it's a lot easier than you're used to. :)
 

Similar threads

  • · Replies 11 ·
Replies
11
Views
3K
  • · Replies 2 ·
Replies
2
Views
3K
  • · Replies 9 ·
Replies
9
Views
2K
  • · Replies 1 ·
Replies
1
Views
4K
  • · Replies 6 ·
Replies
6
Views
3K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 3 ·
Replies
3
Views
3K
  • · Replies 3 ·
Replies
3
Views
4K
  • · Replies 8 ·
Replies
8
Views
2K
  • · Replies 2 ·
Replies
2
Views
4K