If you study arithmetic for long enough, you’ll probably have cursed Pythagoras’s name or, if you’re a devotee of triangles, exclaimed “Praise be to Pythagoras”.
Despite his significance in the history of mathematics, Pythagoras was unable to solve the equation most commonly associated with him, a2 + b2 = c2. The Pythagorean theorem is used in an old Babylonian tablet (known by the enticing name of IM 67118) to calculate the length of a diagonal inside a rectangle. The tablet, which was probably used for instruction, was made around 1770 BCE, which was centuries before Pythagoras, who was born in 570 BCE.
A further tablet from around 1800–1600 BCE features a square with triangles inside that have labels. The Pythagorean theorem (not named that, of course) and other sophisticated mathematical ideas were known to these ancient mathematicians, as evidenced by translating the marks into base-60, the numbering system employed by the Babylonians.
“There is no escaping the conclusion. Mathematician Bruce Ratner notes in a study on the subject, “The Babylonians knew the relation between the length of a square’s diagonal and its side: d=square root of 2.” This was most likely the first known irrational number. But this also implies that they knew about the Pythagorean Theorem more than a millennium before the great philosopher after whom it was named, or at the very least, they were familiar with its specific case for the diagonal of a square (d2 = a2 + a2 = 2a2).”
Why, therefore, was Pythagoras credited with this? Pythagoras left no original writings that have survived. The Pythagoreans, who attended a school he founded in what is now southern Italy, are mostly responsible for what is known about him by other people. The Semicircle of Pythagoras was a hidden school, yet knowledge gained or acquired there was shared and frequently credited to the man.
“One reason for the rarity of Pythagoras sources was that Pythagorean knowledge was passed on from one generation to the next by word of mouth, as writing material was scarce,” Ratner said. “Moreover, out of respect for their leader, many of the discoveries made by the Pythagoreans were attributed to Pythagoras himself; this would account for the term ‘Pythagoras’ Theorem’.”
Even though Pythagoras did not originate the idea, his school undoubtedly promoted it, and for the next few millennia at least, it was linked to him.