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# Mystery Revealed: Ancient mathematical clay tablet proves that Greeks didn't develop trigonometry

## Hipparchus - the Greek astronomer, who lived in about 120 BC -was long been regarded as the father of trigonometry.

Edited by: India TV Buzz Desk, New Delhi [ Published on: August 26, 2017 12:11 IST ]

A 3700-year-old broken mathematical clay tablet has proved that Babylonians trumped the Greeks in developing trigonometry by 1000 years. The usage of clay tablet which was found in southern Iraq in the early 1990s was unknown till now but now a team from the University of New South Wales in Sydney believes it to be the world's oldest and most accurate trigonometric table. It was possibly used by ancient mathematical scribes to calculate how to construct palaces and temples and build canals.

Known as Plimpton 322, the small tablet has four columns and 15 rows of numbers written on it in the cuneiform script of the time using a base 60, or sexagesimal, system. "Plimpton 322 was a powerful tool that could have been used for surveying fields or making architectural calculations to build palaces, temples or step pyramids," said Daniel Mansfield, scientists at the University of New South Wales in Australia.

Until now, the widely accepted view was that the tablet was a teacher's aid for checking students' solutions of quadratic problems."The huge mystery, until now, was its purpose- why the ancient scribes carried out the complex task of generating and sorting the numbers on the tablet," Mansfield said. "Our research reveals that Plimpton 322 describes the shapes of right-angle triangles using a novel kind of trigonometry based on ratios, not angles and circles. It is a fascinating mathematical work that demonstrates undoubted genius," he said in the paper published in the journal Historia Mathematica.

Hipparchus - the Greek astronomer, who lived in about 120 BC -was long been regarded as the father of trigonometry. His "table of chords" on a circle was considered as the oldest trigonometric table. But "Plimpton 322 predates Hipparchus by more than 1,000 years," said Norman Wildberger, Associate Professor, UNSW.  Further, the 15 rows on the tablet were deciphered as a sequence of 15 right-angle triangles, which are steadily decreasing in inclination.

The researchers also demonstrated how the ancient scribes, who used a base 60 numerical arithmetic similar to our time clock, rather than the base 10 number system we use, could have generated the numbers on the tablet using their mathematical techniques. "With Plimpton 322 we see a simpler, more accurate trigonometry that has clear advantages over our own," Wildberger noted.

It belongs to the ancient Sumerian city of Larsa dated to between 1822 and 1762 BC and was discovered by an American archaeologist, Edgar Banks. The tablet which could have changed the method of calculation today is now available in the Rare Book and Manuscript Library at Columbia University in New York.

(With IANS inputs)