Write the Word or Phrase That Best Completes Each Statement $\varepsilon$

Essay

Write the word or phrase that best completes each statement or answers the question.
-If two sound sources at the same volume are equidistant from a microphone, the pressure on the microphone is $\varepsilon$ by
$$p = a \cos \omega _ { 1 } t + a \cos \omega _ { 2 } t$$
where $a _ { , } \omega _ { 1 } , \omega _ { 2 }$ are constants and $t$ is time. Write $\mathrm { p }$ as a product of cosine functions.