## Quick Reference

Suppose that the complex number *z* is represented by the point *P* in the complex plane. The argument of *z*, denoted by arg *z*, is the angle *θ* (in radians) that *OP* makes with the positive real axis *Ox*, with the angle given a positive sense anticlockwise from *Ox*. As with polar coordinates, the angle *θ* may be taken so that 0≤arg *z*<2*π*. Usually, however, the angle *θ* is chosen so that −*π*<arg *z*≤*π*. Sometimes, arg *z* is used to denote any of the values *θ*+2*n**π*, where *n* is an integer. In that case, the particular value that lies in a certain interval, specified or understood, such as [0, 2*π*) or (−*π*, *π*], is called the principal value of arg *z*.

*Subjects:*
Mathematics.

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