WT48: Red geometry (III)
Remarkably, the main laws of trigonometry in the relativistic (red) setting are exactly the same as those in the Euclidean setting. To establish this, we show first that the Cross law---the most powerful law---holds in red geometry. Then the others, such as Pythagoras, the Triple quad formula, the Spread law and the Triple spread formula, follow much as they do in ordinary (blue) geometry. This video is part of the WildTrig series, which introduces Rational Trigonometry and applies it to many different aspects of geometry.