Exploring the Limit of Cosine at Infinity in Integrals

In summary, the conversation discusses an integral with bounds from zero to infinity, which is an improper integral. The limit for evaluating the antiderivative is lim_k->∞ sin(kx)/x and it does not exist due to the endless oscillation of sin(kx). There is no substitution trick for evaluating this integral.
  • #1
maverick_76
19
1
okay so I have this integral:

2∫cos(kx)dk

The bounds are from zero to infinity, this doesn't converge but is there any other way to describe this?
 
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  • #2
maverick_76 said:
okay so I have this integral:

2∫cos(kx)dk

The bounds are from zero to infinity, this doesn't converge but is there any other way to describe this?
Like this? ##2\int_0^{\infty}\cos(kx) dk##
Because the upper limit of integration is ∞, this is an improper integral. You can't just "plug in" ∞ when you evaluate the antiderivative -- you need to use limits to evaluate it.
 
  • #3
okay so the limit would be lim_k->∞ sin(kx)
xHow would I go about evaluating it? Is there a substitution trick?
 
  • #4
maverick_76 said:
okay so the limit would be lim_k->∞ sin(kx)
xHow would I go about evaluating it? Is there a substitution trick?
The limit doesn't exist because sin(kx) oscillates endlessly.
 
  • #5
okay gotcha. Thanks!
 

FAQ: Exploring the Limit of Cosine at Infinity in Integrals

What is the value of cosine evaluated at infinity?

The value of cosine evaluated at infinity is undefined or "does not exist".

Does cosine approach a certain value as the input approaches infinity?

No, cosine does not approach a specific value as the input approaches infinity. It oscillates between -1 and 1 infinitely.

Can cosine be evaluated at infinity using a calculator?

No, most calculators do not have the capability to evaluate functions at infinity. However, you can use the limit definition of cosine to approximate its value at large input values.

How does cosine behave as the input approaches infinity?

As the input approaches infinity, cosine oscillates between -1 and 1 infinitely. It does not approach a specific value or "converge".

Is the concept of cosine evaluated at infinity useful in real-world applications?

No, the concept of cosine evaluated at infinity is mostly used in theoretical mathematics and has limited practical applications.

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