Rational Trigonometry/3

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Spreads, Angles, and Astronomy

Spread
Angles-being-measured-in-degrees originated with the Babylonians and other ancient civilizations practicing spherical trigonometry, as they attempted to begin astronomy. The appearance – that we are inside a rotating sphere – gave rise to the practice using Babylonians multiples of 60 to name angles. A better practice for planar trigonometry is to use spread. Spread is the quadrance of the opposite side, over the quadrance of the hypotenuse.



Spreads vary between 0 and 1. Zero is parallel. One is perpendicular.