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Computing (FOLDOC) dictionary (also found in English - English (Wordnet), English - Vietnamese)
complex number
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mathematics A number of the form x+iy where i is the square
root of -1, and x and y are real numbers, known as the
"real" and "imaginary" part. Complex numbers can be plotted
as points on a two-dimensional plane, known as an Arganddiagram, where x and y are the Cartesian coordinates.
An alternative, polar notation, expresses a complex number
as (r e^it) where e is the base of natural logarithms, and r
and t are real numbers, known as the magnitude and phase. The
two forms are related:
r e^it = r cos(t) + i r sin(t)
= x + i y
x = r cos(t)
y = r sin(t)
All solutions of any polynomial equation can be expressed as
complex numbers. This is the so-called Fundamental Theoremof Algebra, first proved by Cauchy.