(Lecture: 20 minutes)

• Interpret hyperbolic trig functions as speed (and gamma)
• Addition formula
• Lorentz transformations

See §5.2 and §6.1 of the text.

This lecture finally relates hyperbolic trig to velocity, showing that Lorentz transformations are nothing more than hyperbolic rotations — and the Einstein addition formula is nothing more than the addition formula for hyperbolic trig functions.