One of the fascinating points observations about a circle is that the circle is a pure abstraction. It does not exist really anywhere but in our minds as a perfect abstraction of all points equally distant from a one single point, the circle center. No perfect circle can be found in nature, only approximations of it, and each one will have some imperfections, yet the major theories are based of this unexcited in nature geometrical figure. The same can be said for triangle, square, and most of other geometric figures.
Extrapolating these thoughts to electrical engineering, for example three-phase power systems are built around electric fields that by construction are with phase difference of 120 degrees, no ideal voltage is produced that calculates exactly sin and cos functions for the circuitry analyses (this includes complex numbers, that translates to active and reactive power in electric power systems).