At the NASS conference we got into a discussion on who invented trigonometry. I knew that the Greeks were great on geometry but thought that trig functions and tables were a later development, from the early Renaissance.
A quick web search on the question "Who invented trigonometry?" turned up the name of Levi ben Gerson. In 1342 he wrote "On Sines, Chords and Arcs" which developed the mathematical principles of trigonometry and provided 5 figure sine tables. He is best known for developing the algorithm for extracting square roots that we all learned in high school and then forgot. He also invented the forestaff for measuring angular distances essential for celestial navigation. His trig tables were developed for use with the forestaff or "Jacob's staff" See <http://www.math.bme.hu/mathlist/Mathematicians/Levi.html>. Was I right? No! A search at the local library, subsequently confirmed on the web, takes the invention of trig back to the Greek astronomer/mathematicians, in particular to Hipparchus. He produced a table of chords in 140 BC. Menelaus and Ptolemy later extended this work. Hindu mathematicians about 500 AD produced tables of half cords using the name now interpreted as Sine. So Hipparcus is the founder of trigonometry. It goes way back! See <http://history.math.csusb.edu/HistTopics/Trigonometric_functions.html>. This brought home to me how dark the Dark Ages were in Europe. Our Eurocentric view often misses the fact that civilization disappeared in Europe for about 800 years. Today, Nov 11, Remembrance Day, reminded me of recent events that show we are still at it! For an interesting spin on this topic see the book by Thomas Cahill "How the Irish Saved Civilization". His premise is that Irish monks on the fringes of Europe continued to copy not only the bible but the works of the earlier civilizations. The Renaissance was based on this collected knowledge. Roger Bailey N 51 W 115
