If cos(pi*n) = (-1)^n is cos(-pi*n) = (-1)^n

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SUMMARY

The discussion confirms that for the cosine function, the equation cos(-πn) = (-1)^n holds true, given that cos(x) is an even function. This means that cos(-x) equals cos(x) for all x, including integer multiples of π. The user sought clarification on this property while working on a Fourier series integral, and the consensus is that the even nature of the cosine function validates their reasoning.

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mrmerchant786

Homework Statement


i wassolving a Fourier series integral, and needed some help
if cos(pi*n) = (-1)^n is cos(-pi*n) = (-1)^n ?

Homework Equations


i think it is because cos is an even function so -x of the function should still remain the same, because if you look at the graph and flip it its still the same graph

if someone could reply to confirm my thoughts or tell me why its wrong, that would be great thanks :)

The Attempt at a Solution

 
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mrmerchant786 said:

Homework Statement


i wassolving a Fourier series integral, and needed some help
if cos(pi*n) = (-1)^n is cos(-pi*n) = (-1)^n ?

Homework Equations


i think it is because cos is an even function so -x of the function should still remain the same, because if you look at the graph and flip it its still the same graph

if someone could reply to confirm my thoughts or tell me why its wrong, that would be great thanks :)

The Attempt at a Solution


you are correct because ##\cos (x) = \cos (-x)##.
 
Buffu said:
you are correct because ##\cos (x) = \cos (-x)##.
thanks :smile:, thought so
 

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