The sine anecdote in Kovalevskaya’s memoirs

In Sofya Vasilyevna Kovalevskaya’s memoirs there is a rather ambiguous story about how she came to understand trigonometric functions on her own as a teenager by reading the chapter on optics in Tyrtov’s elementary physics textbook. Furthermore, she claims that in so doing, she happened to follow ‘the same road that had been taken historically: that is, instead of a sine I used a chord’. We examine Tyrtov’s textbook in search of sources for such inspiration and quote hitherto unknown critical reactions to her autobiographical reflections by Kovalevskaya’s teacher I I Malevich. We conclude that Kovalevskaya’s memoirs may well be marred by personal interests and/or faltering memory. By adding new sources about Kovalevskaya’s early mathematical education and by critiquing some previously published reactions to the sine anecdote, we hope to contribute some nuances to the biographical literature on this world-famous pioneering female professor of mathematics.