Editing Addition (section)

=== Complex numbers ===
[[File:Vector Addition.svg|right|thumb|Addition of two complex numbers can be done geometrically by constructing a parallelogram.]]
Complex numbers are added by adding the real and imaginary parts of the summands.<ref>{{Citation |last=Conway |first=John B. |title=Functions of One Complex Variable I |year=1986 |publisher=Springer |isbn=978-0-387-90328-6}}</ref><ref>{{Citation |last1=Joshi |first1=Kapil D
|title=Foundations of Discrete Mathematics |publisher=[[John Wiley & Sons]] |location=New York |isbn=978-0-470-21152-6|year=1989}}</ref> That is to say:
:<math>(a+bi) + (c+di) = (a+c) + (b+d)i.</math>
Using the visualization of complex numbers in the complex plane, the addition has the following geometric interpretation: the sum of two complex numbers ''A'' and ''B'', interpreted as points of the complex plane, is the point ''X'' obtained by building a [[parallelogram]] three of whose vertices are ''O'', ''A'' and ''B''. Equivalently, ''X'' is the point such that the [[triangle]]s with vertices ''O'', ''A'', ''B'', and ''X'', ''B'', ''A'', are [[Congruence (geometry)|congruent]].