%0 Journal Article %T Professor £¿¨¹kr¨¹ [Sayan (1884-1943)] %A Ali Y. Baltac£¿o£¿lu %J - %D 2019 %X An article recently published in Osmanl£¿ Bilimi Ara£¿t£¿rmalar£¿ [20, 1 (2019): 102123] by Semiha Bet¨¹l Tak£¿cak analysed £¿¨¹kr¨¹ Sayan¡¯s article on imaginary quantities that was appended to his book on analytic geometry, namely the Hendese-i Tahl£¿liyye (vol.1, £¿stanbul, 1915). The same article noted that no detailed information was available on £¿¨¹kr¨¹ Sayan¡¯s life, a professor of analytic geometry at the Faculty of Science of the Dar¨¹lf¨¹nun. Based on documents kept in author¡¯s personal archives, the present addendum aims to present biographical information on £¿¨¹kr¨¹ Sayan, including his year of birth, birth place, education and professional life, Besides it discloses Sayan¡¯s work on Feuerbach¡¯s nine-point circle published in Hasan Fehmi £¿ayk£¿y¡¯s F£¿yerbah Temas Nazariyesi (Feurebach¡¯s theorem), dated 1921 %K £¿¨¹kr¨¹ Sayan %K Dar¨¹lf¨¹nun %K analitik geometri %K Hasan Fehmi £¿ayk£¿y %K Feuerbach dokuz nokta £¿emberi %U http://dergipark.org.tr/iuoba/issue/46727/544466