A Lissajous curve is a parametric curve in dimension 2,
described by a pair of functions
These curves occur often in the study of electronics.
They form a good example of parametric curves.
This online exercise can either plot a Lissajous curve and
ask you to recognize its equations among a list to choose from,
or give a pair of equations and ask you to recognize the plotted Lissajous
curve among a list to choose from.