Demo: Determine quintic by 3 stationary points

Note - there's a much better way of doing this, see [url=https://www.geogebra.org/m/nbjfuvya]www.geogebra.org/m/nbjfuvya[/url]
Derivation (using CAS)
– Michael Borcherds

Information: Demo: Determine quintic by 3 stationary points