This Argand diagram
shows how complex numbers a and b are subtracted to produce the
complex number c. This subtraction is similar to the "parallelogram law"
for subtracting vectors.
Summary
the Argand diagram illustrates
a - b = c, where a, b and c are
complex numbers
if a = c + di and
b = e + fi, then c = a - b = (c-e) +
(d-f)i