SOLUTION: Two frequencies of sound are played on an instrument governed by the function n(t)=8cos(20πt)cos(1000πt). What is the period and frequency of the fast and slow oscillation? What

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Question 1161878: Two frequencies of sound are played on an instrument governed by the function n(t)=8cos(20πt)cos(1000πt). What is the period and frequency of the fast and slow oscillation? What is the amplitude?
Answer by ikleyn(52781) About Me  (Show Source):
You can put this solution on YOUR website!
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cos(a)*cos(b) = %281%2F2%29%2Acos%28a-b%29 + %281%2F2%29%2Acos%28a%2Bb%29.


There are two harmonic modes in this instrument.


The low frequency is %281000-20%29%2F2 Hertz = 490 Hertz;  the period is  1%2F490 of a second.


The high frequency is %281000%2B20%29%2F2 Hertz = 510 Hertz;  the period is  1%2F510 of a second.


The amplitude is 4 units for each harmonic mode.