Professor ？ükrü [Sayan (1884-1943)]

An article recently published in Osmanl？ Bilimi Ara？t？rmalar？ [20, 1 (2019): 102123] by Semiha Betül Tak？cak analysed ？ükrü 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 ？ükrü Sayan’s life, a professor of analytic geometry at the Faculty of Science of the Darülfünun. Based on documents kept in author’s personal archives, the present addendum aims to present biographical information on ？ükrü 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