What is the Exact Solution to 0.739085?

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Discussion Overview

The discussion revolves around the exact expression of the solution to the equation cos(x) = x, which is approximately 0.739085. Participants explore whether this solution can be represented exactly using constants such as pi, e, and the golden ratio (phi).

Discussion Character

  • Exploratory
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant states that the solution is approximately 0.739085 and inquires about expressing it exactly in terms of known constants.
  • Another participant suggests that it is likely impossible to express the solution simply.
  • A different participant proposes a formula involving the constants pi, e, and phi, suggesting a potential expression for the solution.
  • One participant refines the earlier claim, indicating that expressing the solution in a finite manner using the specified constants and integers is very likely impossible.
  • There is a mention that not all transcendental numbers can be expressed using only e, pi, and algebraic numbers, indicating a broader limitation in representation.
  • A participant expresses uncertainty about the possibility of expressing the solution and suggests assigning it a Greek letter instead.
  • Another participant asserts that it is impossible to express the solution in the desired form.
  • One participant introduces the concept of applying the cosine function infinitely to a starting point as a method to express the solution, referencing the Contraction Mapping Theorem.

Areas of Agreement / Disagreement

Participants express differing views on the possibility of expressing the solution exactly. Some argue it is impossible, while others propose potential expressions, leading to an unresolved discussion.

Contextual Notes

There are limitations regarding the assumptions made about the nature of transcendental numbers and their expressibility in terms of specific constants. The discussion also touches on the mathematical framework of the Contraction Mapping Theorem without resolving the implications.

Antiphon
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The solution to this equation is approximately 0.739085.

Does anyone know how to express the solution exactly
in terms of contants like pi, e, phi, etc?

(phi = golden ratio = 1/2 + sqrt(5)/2)
 
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In all likelyhood it's impossible to do so in a simple way.
 
Sure it is.If "x" is a solution to the equation,then be can expressed as

[tex]x=\frac{x}{\pi e\varphi} \pi e\varphi[/tex]

Daniel.
 
You're right, of course. I took some license in my interpretation of his question. I'll be more precise:

It's very likely impossible to express the solution in terms of a finite number of products, extractions of roots, additions, exponentiations, and divisions of elements of the set [tex]\{e, \pi, \phi\} \cup \mathbb{Z}[/tex]

~
 
Last edited:
Let's tell Antiphon that not all transcendental numbers can be written using only [itex]e[/itex] and [itex]\pi[/itex] and the set of algebraic numbers...

Daniel.
 
dextercioby said:
Let's tell Antiphon that not all transcendental numbers can be written using only [itex]e[/itex] and [itex]\pi[/itex] and the set of algebraic numbers...

Daniel.

I suspected this, but I asked the question assuming it was possible.

So then you think it's impossible or you're not sure in this case?

Perhaps then I should assign it a greek letter!
 
1.It is impossible.

2.You should.

Daniel.
 
The solution of the equation cos (x) = x can be given as applying the cosine function infinite nubmer of times to a starting point ..

x = cos cos cos ... cos (a)

In other words , the solution can be expressed as :

[tex]x = \lim _ { n \to \infty } \cos ^ { \circ n } ( a )[/tex]


That came from the Contraction Mapping Theorem .
 

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