Question

Use a graphing utility to graph the sound emitted by the * key on a Touch-Tone phone. See Problem 53.

Short answer

The required graph is

Step-by-step solution

Step 1. Given Information

The given figure is

Step 2. Explanation

On a touch-tone phone, each button produce a unique sound and the sound produced is the sum of two tones.

For the button key *, the low frequency is 941 cycles per second and high is 1209 cycles per second.

Thus, the sound emitted by touching * is given by,

$$\begin{gathered} y=\sin \left(2\mathrm{\pi lt}\right)+\sin \left(2\mathrm{\pi ht}\right) \\ \mathrm{y}=\sin \left(2\mathrm{\pi }\right(941\left)\mathrm{t}\right)+\sin \left(2\mathrm{\pi }\right(1209\left)\mathrm{t}\right) \\ \mathrm{y}=\sin \left(1882\mathrm{\pi t}\right)+\sin \left(2418\mathrm{\pi t}\right) \end{gathered}$$

Thus, the graph of the obtained function is