To find a definition for the square root that allows us to consistently choose a single value, called the principal value, we start by observing that any complex number "x" + "iy" can be viewed as a point in the plane, ("x", "y"), expressed using Cartesian coordinates. The same point may be reinterpreted using polar coordinates as the pair formula_28), where "r" ≥ 0 is the distance of the point from the origin, and formula_29 is the angle that the line from the origin to the point makes with the positive real ("x") axis. In complex analysis, the location of this point is conventionally written formula_30 If