Person: Fagnano, Giulio

Giulio Fagnano was an Italian mathematician who worked in both complex numbers and on the geometry of triangles.

Giulio was born into one of the leading families in Sinigaglia.
The town of Sinigaglia, now known as Senigallia, is in central Italy and at the time of Giulio's birth was part of the Papal States.
Such offices were not easy in these times and Fagnano was subjected to many false charges made against him by envious citizens who were maliciously trying to damage his reputation.
Giulio Fagnano was self educated in mathematics and treated the subject as a hobby.
Fagnano suggested new methods of solving equations of degree 2, 3 and 4.
One of the topics for which Fagnano is best known is his work on triangles.
In his study of the rectification of the lemniscate, Fagnano introduced ingenious analytic transformations that laid the foundation for the theory of elliptic integrals and his work was to lead to elliptic functions.
Fagnano collected many of his published works, and a few unpublished ones, and produced the two volume treatise Produzioni matematiche Ⓣ(Mathematical Productions) in 1750.
Generalising Fagnano's results, Euler went on to create a general theory of these integrals, in particular giving the famous addition formula for elliptic integrals.
Fagnano had proved the duplication formula, a particular case of the addition formula, for the integrals.
Fagnano made many other major contributions but his mathematical work was not without controversy.
Fagnano received many honours.

Born 6 December 1682, Sinigaglia (now Senigallia, Italy). Died 26 September 1766, Sinigaglia (now Senigallia, Italy).

View full biography at MacTutor

Origin Italy, Physics

Thank you to the contributors under CC BY-SA 4.0!

O’Connor, John J; Robertson, Edmund F: MacTutor History of Mathematics Archive