Drexel dragonThe Math ForumDonate to the Math Forum



Search All of the Math Forum:

Views expressed in these public forums are not endorsed by Drexel University or The Math Forum.


Math Forum » Discussions » Math Topics » geometry.college.independent

Topic: Nonperiodic Trigonometric functions
Replies: 0  

Advanced Search

Back to Topic List Back to Topic List  
Batu

Posts: 3
From: New Jersey
Registered: 11/22/11
Nonperiodic Trigonometric functions
Posted: Nov 22, 2011 9:16 AM
  Click to see the message monospaced in plain text Plain Text   Click to reply to this topic Reply

Is the function
f(x)=sin(sqrt(2)x)cos(sqrt(3)x) periodic?

If yes, what is the period?

If not, how to prove it?

In general, if a and b are irrational numbers so that ab is not rational, is
f(x)=sin(ax)cos(bx) periodic?

If yes, what is the period?

If not, how to prove it?

My suggested 'proof' involves using successive decimal approximations for a and b, so the period grows larger as the denominator of the decimal approximation grows larger, thus the period 'goes to infinity'.
But I can't find a reference for this type of reasoning.



Point your RSS reader here for a feed of the latest messages in this topic.

[Privacy Policy] [Terms of Use]

© Drexel University 1994-2014. All Rights Reserved.
The Math Forum is a research and educational enterprise of the Drexel University School of Education.