Period of a sum of cosine signals

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SUMMARY

The period of the signal x(t) = 2 + 4cos(40πt) + 3cos(60πt) + 4cos(120πt) is determined by the fundamental frequency, which is 10 Hz. This frequency is the greatest common factor of the individual frequencies of the cosine components: 20 Hz, 30 Hz, and 60 Hz. The overall period of the signal is 0.1 seconds, as calculated by taking the reciprocal of the fundamental frequency. The professor deducted points likely due to a misunderstanding of the individual periods of each cosine component.

PREREQUISITES
  • Understanding of trigonometric functions, specifically cosine
  • Knowledge of frequency and period relationships
  • Familiarity with signal analysis concepts
  • Basic algebra for calculating greatest common factors
NEXT STEPS
  • Study the relationship between frequency and period in trigonometric functions
  • Learn about the concept of fundamental frequency in signal processing
  • Explore the effects of adding multiple cosine signals on overall signal characteristics
  • Investigate the implications of phase shifts in cosine signals
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Students in electrical engineering, signal processing enthusiasts, and anyone studying harmonic analysis in waveforms.

Quincy
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Homework Statement


Find the period of the signal x(t) = 2 + 4cos(40Pi*t) + 3cos(60Pi*t) + 4cos(120Pi*t).


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The Attempt at a Solution



The fundamental frequency (fo) = 10 Hz, since that's the greatest common factor of all the frequencies of the cosine signals. So the period would be 1/10 = 0.1 s. But my professor took points off for it, why?
 
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how many times per sec does each component of the signal by itself repeat?

How much time does each component of the signal take to go through one cycle?
 

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