• Support PF! Buy your school textbooks, materials and every day products Here!

Proof of Periodic Sinusoidal waveforms

  • Thread starter tomh
  • Start date
1
0
1. Homework Statement
Hi,

Have completely forgotten how to prove that a sinusoidal waveform is periodic and can't seem to find it anywhere. So was hoping someone could here.

I've got the signal x(t)=cos(2t+pi/4)

and am trying to prove it is periodic.

2. Homework Equations

wt=theta

f(x+k)=f(x)

cos(x)=sin(x+pi/2)

3. The Attempt at a Solution

I know that it is periodic, but to prove I think I have to prove that x(t)=0

Have tried letting t=-pi/8 but with the phase change of pi/2 to convert it to a sine again it gives me a non zero answer.

Anyone with any help would be greatly appreciated.
 

tiny-tim

Science Advisor
Homework Helper
25,790
249
welcome to pf!

hi tomh! welcome to pf! :smile:

(have a pi: π and a theta: θ :wink:)

cos(A + 2πn) = cosAcos2πn - sinAsin2πn = cosA

does that help?​
 

Related Threads for: Proof of Periodic Sinusoidal waveforms

  • Last Post
Replies
1
Views
2K
Replies
3
Views
3K
Replies
6
Views
8K
  • Last Post
Replies
3
Views
2K
  • Last Post
Replies
4
Views
7K
  • Last Post
Replies
1
Views
4K
  • Last Post
Replies
3
Views
11K
Replies
3
Views
1K
Top