 Fermat's rule for maxima and minima by the Garden of Archimedes

University of Florence mathematical-museum exhibition, Analytical geometry and the problem of tangents. It gives a translation and reconstruction of Pierre de Fermat's parabola example, using the letters B, C, D, E, I, O of the exam image. The text distinguishes circulation in the 1630s from the 1679 publication. Its final displayed label contains a typographical anomaly; the derivation and geometry give $CE=2CD$.

Online source: archimede.dimai.unifi.it/archimede/archimede_NEW_inglese/mostra_calcolo/guida/node7.html