The degree of f is called the degree or order of the curve. Curves of degree three already have a great variety of shapes, and only a few common ones will be given here. The folium of Descartes is a rational curve , this is, it has a parametric representation by rational functions. The folium of Descartes in two positions, and the strophoid. The middle curve is the cardioid, the one on the right a trisectrix.
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