This is excellent. I'm always looking for good things to show my students on coordinate systems and geometry, and this joins the list. Thank you for diving down the rabbit hole and bringing this back for everyone.

If you want really great further consideration of creating geometric figures with parametric equations, Joseph Choma's book "Morphing" is an all-timer.

https://www.quercusbooks.co.uk/titles/joseph-choma/morphing/...

oh wow, the book looks nice. thanks for the recommendation!