Problem with the fourier series

Click For Summary

Homework Help Overview

The discussion revolves around a problem related to Fourier series, specifically focusing on the properties of the cosine function and its periodicity.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants are questioning the values of cosine at specific points, such as cos(0), cos(π), and cos(2π), and discussing the implications of these values in relation to the periodicity of the cosine function.

Discussion Status

There is an active exploration of the periodic nature of the cosine function, with participants providing differing interpretations of its period and questioning assumptions about the values of cos(nπ). Some guidance has been offered regarding the periodicity of cosine and the values at specific multiples of π.

Contextual Notes

Participants are navigating potential misunderstandings about the periodicity of the cosine function and its values at integer multiples of π, with some expressing uncertainty about the implications of these values in the context of the Fourier series problem.

robertjford80
Messages
388
Reaction score
0

Homework Statement



this comes from a problem with the Fourier series

Screenshot2012-06-12at52252AMcopy.png



The Attempt at a Solution



I don't get the above step.
 
Physics news on Phys.org
What is cos(0)? How about cos(π)? cos(2π)? What's the period of cosine?
 
here's another photo. I think the period is pi, but I would think cos npi would simplify to 1 not -1
 
I have no idea why you would think that! Surely you know that [itex]cos(\pi)= -1[/itex]?
 
robertjford80 said:
here's another photo. I think the period is pi, but I would think cos npi would simplify to 1 not -1

The period of cos is not ∏. Think at what intervals does cos give you the same numbers it was giving for the previous interval?

In other words,

[tex]cos(T+x) = cos(x)[/tex]

For which smallest non-zero, positive value of T??Also, cos(n∏) has both the possibilities of being cos(∏) at n=1 and cos(2∏) at n=2. What are the values of each?
 

Similar threads

  • · Replies 3 ·
Replies
3
Views
2K
Replies
3
Views
2K
Replies
3
Views
2K
  • · Replies 2 ·
Replies
2
Views
1K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 5 ·
Replies
5
Views
1K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 20 ·
Replies
20
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K