The sound waves are illustrations of cosine functions
The frequencies of the sound waves are x = 90°, 120°, 240°, 270°
The equations of the sound waves are given as:
[tex]y = 2\cos^2(x)[/tex]
[tex]y =-\cos(x)[/tex]
Next, we plot the graphs of the functions [tex]y = 2\cos^2(x)[/tex] and [tex]y =-\cos(x)[/tex]
From the graphs of the functions (see attachment), we have the following x-coordinates of the points of intersection of the both curves between the interval [0°, 360°)
[tex]x =(\frac{\pi}{2},\frac{2\pi}{3},\frac{4\pi}{3},\frac{3\pi}{2})[/tex]
Express as degrees
[tex]x =(90^o,120^o, 240^o, 270^o)[/tex]
Hence, the frequencies of the sound waves are x = 90°, 120°, 240°, 270°
Read more about sound waves at:
https://brainly.com/question/2285154