e^τi = 1. In words, this equation makes the following fundamental observation: The complex exponential of the circle constant is unity. Geometrically, multip

e^τi = 1. In words, this equation makes the following fundamental observation: The complex exponential of the circle constant is unity. Geometrically, multiplying by e^iθ corresponds to rotating a complex number by an angle θ in the complex plane, which suggests a second interpretation of Euler’s identity: A rotation by one turn is 1. The Tau Manifesto http://tauday.com/tau-manifesto#sec-euler_s_identity http://tauday.com/tau-manifesto#sec-euler_s_identity