Kou (hook) is a "right-angled hook," meaning two short sides containing a right angle; Ko (thigh) is a "leg joint," meaning a long side; and Gen (chord) is a "bowstring," meaning a hypotenuse. This theorem was also discovered in ancient Babylonia and ancient India, and regarded as an important theorem used in surveying, architecture, astronomical observations, etc. The trigonometric functions are also closely related to the Pythagorean Theorem.
I haven't learned the word 'Kou' in the class which means a right-angled hook so I call it 'Kouhook' instead.
by worldcafe November 22, 2021