x=sin(3θ+δ), y=sin(2θ)
Crossings: a closed Lissajous with ratio a:b has (a+b−2) interior crossings when gcd(a,b)=1.
Ratio a/b rational → periodic closed curve.
Ratio irrational → dense, never closes.
Ratio a/b rational → periodic closed curve.
Ratio irrational → dense, never closes.
Closed curve (gcd=1)