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August 19th, 2009, 10:06 PM  #1 
Newbie Joined: May 2009 Posts: 20 Thanks: 0  periodic/not periodic functions application to electronics
one of the following functions is periodic and the other is not: f(t) = cos(10(pi)t)+3sin(4(pi)t) g(t) = cos(10t)+3sin(4(pi)t) which function is peridic? what is the fundamental period of the function? which is not periodic and why isnt it? 
August 20th, 2009, 05:36 AM  #2 
Member Joined: Jul 2009 Posts: 34 Thanks: 0  Re: periodic/not periodic functions application to electronics
The functions sin(at) and cos(at) are periodic and their period is . If we look at , then we see that the cosine has period , and that the sine has period . Which means that for every 5 periods of the cosine, there are 2 periods of the sine, and hence it's also 1 period of the sum, f(t). The length of this period is then 1. But if we look at , the period of the cosine is and that of the sine is . In this case, we can't say that a whole number of periods of the cosine is equal to a whole number of periods of the sine. Hence we can't point out a period for the sum of them, g(t). 

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application, electronics, functions, periodic, periodic or not 
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