Irrational numbers in infinite list of integers

In summary, the answer to this question is that for all integer values of x, there exists a number x such that sin(x) is greater than 0.
  • #1
GunnaSix
35
0
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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  • #2
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​
 
  • #3
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.
 
  • #4
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?
 
  • #5
Integer radians. Sorry if this was a super obvious question. I guess I was just thinking too much into it.
 
  • #6
If you mean to ask whether the intervals [2npi,(2n+1)pi) (where sinx >0) contain integers, the answer is yes ( as pi>1).
 
  • #7
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.
 
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  • #8
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.
 
  • #9
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.
 

1. What are irrational numbers?

Irrational numbers are real numbers that cannot be expressed as a ratio of two integers. They are numbers that do not terminate or repeat in decimal form, such as pi (3.14159...) or the square root of 2 (1.41421...).

2. How are irrational numbers different from rational numbers?

Irrational numbers cannot be written as a fraction of two integers, while rational numbers can. Additionally, irrational numbers have decimal representations that never terminate or repeat, while rational numbers have finite or repeating decimal representations.

3. How are irrational numbers represented in an infinite list of integers?

In an infinite list of integers, irrational numbers are represented as approximations. For example, pi can be approximated as 3.14, but it cannot be represented exactly as it has an infinite number of decimal places.

4. Is there a pattern to the occurrence of irrational numbers in an infinite list of integers?

No, there is no pattern to the occurrence of irrational numbers in an infinite list of integers. They are randomly distributed and can occur at any point in the list.

5. Why are irrational numbers important in mathematics?

Irrational numbers are important in mathematics because they allow us to represent quantities that cannot be expressed as a ratio of two integers. They are also essential in fields such as geometry, where they help us understand and describe the relationship between different shapes and their measurements.

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