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

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Question 1161865: Two frequencies of sound are played on an instrument governed by the function n(t)=8cos(20pie*t)cos(1000pie*t). What is the peroid and frequency of the fast and slow oscillation? What is ampmitude?
Found 2 solutions by ikleyn, Alan3354:
Answer by ikleyn(52778) About Me  (Show Source):
You can put this solution on YOUR website!
.

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.



Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
No math problems with pie.
Use the Greek letter pi.