▁brother ▁of ▁phil os opher ▁Ludwig ▁Feuer bach . ▁After ▁receiving ▁his ▁doctor ate ▁at ▁age ▁ 2 2 , ▁he ▁became ▁a ▁professor ▁of ▁mathematics ▁at ▁the ▁G ymnasium ▁at ▁Er lang en . ▁In ▁ 1 8 2 2 ▁he ▁wrote ▁a ▁small ▁book ▁on ▁mathematics ▁noted ▁mainly ▁for ▁a ▁theorem ▁on ▁the ▁nine - point ▁circle , ▁which ▁is ▁now ▁known ▁as ▁Feuer bach ' s ▁theorem . ▁In ▁ 1 8 2 7 ▁he ▁introduced ▁hom ogeneous ▁coordinates , ▁independently ▁of ▁M ö b ius . ▁ ▁Works ▁ ▁. ▁ ▁(" Properties ▁of ▁some ▁special ▁points ▁in ▁the ▁plane ▁of ▁a ▁triangle , ▁M I Y and ▁various ▁lines ▁and ▁figures ▁determined ▁by ▁these ▁points : ▁an ▁analyt ic - tr ig on ometric ▁treatment ") ▁Grund r iss ▁zu ▁analyt ischen ▁Un tersuch ungen ▁der ▁dre ye ck igen ▁Py ram ide ▁(" Found ations ▁of ▁the ▁analyt ic ▁theory ▁of ▁the ▁tri angular ▁py ram id ") ▁ ▁Notes ▁ ▁External ▁links ▁▁▁▁▁ ▁Feuer bach ' s ▁Theorem : ▁a ▁Proof ▁ ▁Karl ▁Wilhelm ▁Feuer bach : ▁Ge ometer ▁▁▁ ▁Category : 1 8 0 0 ▁birth s ▁Category : 1 8 3 4 ▁death s ▁Category : Pe ople ▁from ▁J ena ▁Category : Pe ople ▁from ▁Sax e - We imar ▁Category : G erman ▁Luther ans ▁Category : 1 9 th - century ▁German ▁mathemat icians ▁Category : Ge om eters <0x0A> </s> ▁Lib y the a ▁nar ina , ▁the ▁whites p