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Source: Chinese Pythagorean theorem, from page 22 of Joseph Needham's Science and Civilization in China: Volume 3, Mathematics and the Sciences of the Heavens and the Earth, published in 1986 by Cave Books Ltd., based in Taipei (with permission from Cambridge University Press). isbn:0521058015

Visual proof for the (3, 4, 5) triangle as in the Chou Pei Suan Ching 500–200 BC.
Left sentence: 勾股幂合以成弦幂 (gōu gǔ mì hé yǐ chéng xián mì)
Translation: The sum of the squares of lengths of altitude and base is the hypotenuse's length squared.

Derivative works of this file:  Chineese Pythagorean theorem 2.PNG