We now add more than two plane waves together. We will also ignore the time dependent component of the wave.

The original wave is cos(pi*x),
in which case k = pi.
The other buttons add more components to the original wave. For instance,
the "Add ±0.1*k button" plots in dark blue the function cos(pi*x)+cos(1.1*pi*x)+cos(0.9*pi*x).
The light blue plot is the original wave. There is a change in scale on
the xaxis for the last two buttons.
Student Exercises: