Irrational numbers in infinite list of integers

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Discussion Overview

The discussion revolves around the properties of the sine function, particularly its behavior at integer values, and the relationship between integers and rational numbers. Participants explore whether the absolute value of sin x is greater than zero for all positive integer values of x and the implications of irrational numbers in the context of integers.

Discussion Character

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

Main Points Raised

  • Some participants question whether the absolute value of sin x is greater than zero for all positive integer values of x, expressing uncertainty about the relationship between integers and irrational numbers.
  • Others propose that the conjecture regarding irrational numbers in an infinite list of integers is equivalent to stating that every integer is rational.
  • A participant notes that sin(x) equals zero for positive x only at specific points (x = k*pi), raising concerns about the implications of this for integer values.
  • There is a clarification regarding whether the discussion pertains to integer degrees or radians, with a consensus that it refers to integer radians.
  • Some participants assert that sine is zero only at n*pi radians, suggesting that sine is either greater than or less than zero for any positive integer angle in radians.
  • It is mentioned that all integers can be expressed as fractions (n/1), indicating that all integers are rational numbers, and thus there are no irrational integers.
  • Participants highlight that while sin(n) is never zero for any integer n, this does not imply that sin(n) is always greater than zero, as negative values exist (e.g., sin(4)).

Areas of Agreement / Disagreement

Participants express differing views on the behavior of the sine function at integer values and the implications for rationality and irrationality in integers. There is no clear consensus on whether the absolute value of sin x is greater than zero for all positive integers.

Contextual Notes

Some statements rely on specific interpretations of sine values and the definitions of integers and rational numbers, which may not be universally agreed upon. The discussion includes assumptions about the nature of sine and its values at integer inputs.

GunnaSix
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Is it safe to assume that the absolute value of sin x is greater than zero for all positive integer values of x? I have no real experience in number theory, and I don't know if you can say that there are no irrational numbers in an infinite list of integers.
 
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GunnaSix said:
I don't know if you can say that there are no irrational numbers in an infinite list of integers.
Can you convince yourself that this conjecture is equivalent to
Every integer is rational​
 
If sin(x)=0 for positive x, then x=k*pi for some positive integer k. If x is an integer, then x/k=pi should raise a red flag.
 
GunnaSix said:
Is it safe to assume that the absolute value of sin x is greater than zero for all positive integer values of x? I have no real experience in number theory, and I don't know if you can say that there are no irrational numbers in an infinite list of integers.

are you talking of integer degrees or radians?
 
Integer radians. Sorry if this was a super obvious question. I guess I was just thinking too much into it.
 
If you mean to ask whether the intervals [2npi,(2n+1)pi) (where sinx >0) contain integers, the answer is yes ( as pi>1).
 
Eynstone said:
If you mean to ask whether the intervals [2npi,(2n+1)pi) (where sinx >0) contain integers, the answer is yes ( as pi>1).

SineX = 0 only where X = n*pi radians. But n*pi must be an irrational number or 0. Thus SineX is either greater than or less than 0 for any integer angle n in radians where n>0. I think this is what the poser was asking.
 
Last edited:
GunnaSix said:
Is it safe to assume that the absolute value of sin x is greater than zero for all positive integer values of x? I have no real experience in number theory, and I don't know if you can say that there are no irrational numbers in an infinite list of integers.
Yes, since any integer, n, can be written as the fraction n/1, all integers are rational numbers. There are no irrational integers. It is true that sin(n) is never 0 for any integer n- but that does NOT mean "greater than 0". sin(4) is negative.
 
HallsofIvy said:
Yes, since any integer, n, can be written as the fraction n/1, all integers are rational numbers. There are no irrational integers. It is true that sin(n) is never 0 for any integer n- but that does NOT mean "greater than 0". sin(4) is negative.
While I used the language "Sine x" is "greater than or less than 0", the poser asked whether "the absolute value of Sine x is greater than 0 for all integer values of x.". I think you had my language in mind when you overlook the "absolute value" part of the poser's question.
 

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