Karl Wilhelm Feuerbach (30 May 1800 – 12 March 1834) was a German geometer and the son of legal scholar Paul Johann Anselm Ritter von Feuerbach, and the brother of philosopher Ludwig Feuerbach. After receiving his doctorate at age 22, he became a professor of mathematics at the Gymnasium at Erlangen. In 1822 he wrote a small book on mathematics noted mainly for a theorem on the nine-point circle, which is now known as Feuerbach's theorem. In 1827 he introduced homogeneous coordinates, independently of Möbius.^[1]

• Eigenschaften einiger merkwürdigen Punkte des geradlinigen Dreiecks und mehrerer durch sie bestimmten Linien und Figuren. Eine analytisch-trigonometrische Abhandlung (Monograph ed.), Nürnberg: Wiessner, 1822. online book at Google Books ("Properties of some special points in the plane of a triangle, and various lines and figures determined by these points: an analytic-trigonometric treatment")
• Grundriss zu analytischen Untersuchungen der dreyeckigen Pyramide ("Foundations of the analytic theory of the triangular pyramid")

• Works by or about Karl Wilhelm Feuerbach at the Internet Archive
• O'Connor, John J.; Robertson, Edmund F., "Karl Wilhelm Feuerbach", MacTutor History of Mathematics Archive, University of St Andrews
• Feuerbach's Theorem: a Proof
• Karl Wilhelm Feuerbach: Geometer
• Media related to Karl Wilhelm Feuerbach (geometer) at Wikimedia Commons