A = 6
  a = 6
  t = 6
  δ = 90°
  B = 6
  b = 6

Lissajous curves are graphic patterns that can be obtained through the parametric equations:

x(t) = A sin(at+δ), y(t) = B sin(bt)

The curves describe harmonic vibrations. They were first discovered by Nathaniel Bowditch and later investigated by Jules Antoine Lissajous.