Trigonometry: Secant-ing out New Life in Ancient Civilizations

Plimpton 322 from

It’s irresistible. The siren song of Wikipedia calls to me. All I was trying to do was find out which Greek invented trigonometry. Was it Pythagoras and his bean-renouncing cult or someone else? And I come across this enticing little tidbit, a curious little reference which, to a history buff is like the smell of fresh cookies…

Based on one interpretation of the Plimpton 322 cuneiform tablet (c. 1900 BC), some have even asserted that the ancient Babylonians had a table of secants.[8] There is, however, much debate as to whether it is a table of Pythagorean triples, a solution of quadratic equations, or a trigonometric table.

Wikipedia: History of Trigonometry

Much debate? Some have asserted? This sounds like historical mystery to me. I was instantly overjoyed at the thought of poking around to see if anyone denounced anyone else in the public square or started fistfights or wrote long letters to the editor of scientific journals about how their enemies were cretins who didn’t know a hypotenuse from a hippopotamus. And I wasn’t disappointed.

Don’t Be Afeared, it’s Just Math

First, a few definitions. Even if you’ve never taken trigonometry or if the very word causes you to put a blanket over your head, don’t worry. Imagine that it’s a warm sunny day in Greece (or Babylonia or Sumeria or Egypt) and you notice that the pillar of the nearby temple, next to where you are sunning yourself, throws a shadow. Since you like to measure things, you get out your handy measuring stick and you measure the length of the shadow. You know the length of the pillar. You start doing calculations.

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