A Rotation by One Turn is 1

In Michael Hartl’si Tau Manifestoiiiii, he addresses a criticism of the Tau formulation which points out that the -form of Euler’s equation only relates 4 fundamental constants (e, i, circle constant, and 1), while the -form relates 5 (despite needing to be re-arranged to do so). In response, he jokingly tacks on a trivial ‘+0’ [...]