# Thread: Periodic signal

1. ## Periodic signal

Hi everyone

I really dont know how to start this questions, please help me. Thank you in advance for all your help & support.

Determine if each of the following CT signals is periodic. If periodic find it period.
a) x(t)=2sin(10 $\pi$t-30degrees)
b) x(t) = 2 cos ( $\sqrt$2 $\pi$t)
c)x(t) = 2 sin ( $\sqrt$ $\pi$t)
d) x(t) = 2 cos (t+ 60degrees)

2. ## Re: Periodic signal

Originally Posted by anderson
Hi everyone

I really dont know how to start this questions, please help me. Thank you in advance for all your help & support.

Determine if each of the following CT signals is periodic. If periodic find it period.
a) x(t)=2sin(10 $\pi$t-30degrees)
b) x(t) = 2 cos ( $\sqrt$2 $\pi$t)
c)x(t) = 2 sin ( $\sqrt$ $\pi$t)
d) x(t) = 2 cos (t+ 60degrees)
You're meant to know that the sine and cosine functions are periodic. What knowledge do you have those functions and where are you stuck in applying that knowledge to your current questions?

3. ## Re: Periodic signal

Thank you for your response. Need an example so that I can understand the question. Appreciate if anyone can help to solve.

4. ## Re: Periodic signal

Originally Posted by anderson
Thank you for your response. Need an example so that I can understand the question. Appreciate if anyone can help to solve.
But you haven't yet answered what I asked. Again:

You're meant to know that the sine and cosine functions are periodic. What knowledge do you have those functions and where are you stuck in applying that knowledge to your current questions?

5. ## Re: Periodic signal

Sine and cosine are periodic, i think that is what you are saying. How do i find the period if it is periodic.

6. ## Re: Periodic signal

Originally Posted by anderson
Sine and cosine are periodic, i think that is what you are saying. How do i find the period if it is periodic.
Look, this is the third time I've had to ask: What have you learned about sine and cosine functions?

7. ## Re: Periodic signal

Nothing, that is why I am asking for help. If someone can do the first question, then I can use it as an example. Hope this answers your question.

8. ## Re: Periodic signal

Originally Posted by anderson
Nothing, that is why I am asking for help. If someone can do the first question, then I can use it as an example. Hope this answers your question.
I find that hard to believe. I'm mighty surprised that a subject that would set questions like these does not require knowledge of trigonometric functions as a pre-requisite for enrolment.

If true, I suggest that you review some websites found by Google: Google

For example, About trigonometric functions

Getting a hold of a textbook that covers basic trigonometric functions would also be prudent.

Do you know the difference between degrees and radians? If not, I suggest you review that material as well.

9. ## Re: Periodic signal

Thanks but no thanks.If you can't help, please dont reply. Thank you & regards.

10. ## Re: Periodic signal

Originally Posted by anderson
Thanks but no thanks.If you can't help, please dont reply. Thank you & regards.
OK, I see it's like that. I was trying to help you help yourself. But from the above, you obviously have no interest in reviewing resource material that will help you.

I think it's perfectly reasonable to direct you to resources and request that you review them so that you might be in a better position to make inroads into the questions you posted. After doing so, you can still ask for help, but you'll be able to be more specific on exactly where you're stuck.

Having reviewed your post history, I can surmise from the questions you've posted that you have studied complex numbers, differential equations, calculus of one and several variables, analysis etc.

But you're claiming to have no knowledge of trigonometric functions ....

11. ## Re: Periodic signal

Please dont reply if you cannot help out in any way, dont waste time. Thank you in advance.