A complex number can be viewed as a point in the Argand
diagram (complex plane).
Complex plane is a modified
Cartesian plane, where the real part of the complex number is represented along x axis
and the imaginary part is represented along y axis.
The
rectangular form of a complex number is usually called the algebraic form of the complex
number.
z = x + y*i
x is the
real part of the complex number z - Re(z)
y is the
imaginary part of the complex number z - Im(z)
i =
sqrt(-1)
Also, the Argand diagram helps to determine the
displacement of a point with respect to origin of the complex
plane.
The distance is called the modulus of the complex
number:
|z| = sqrt[Re(z)^2 +
Im(z)^2]
|z| = sqrt(x^2 +
y^2)
The argument of a complex number is the angle made to
real axis, x-axis.
tan a = y/x =
Re(z)/Im(z)
The geometric form of a complex number
is:
z = |z|(cos a + i*sin
a)
Example:
We
have the complex number z = 1 +
i
The given form is the
rectangular form or the algebraic form.
The
real part is:
Re(z) = 1
The
imaginary part is:
Im(z) =
1
Now, we'll write z in polar
form:
z = |z|(cos a + i*sin
a)
We'll calculate the modulus and the argument of the
complex number z:
|z| = sqrt(1^2 +
1^2)
|z| = sqrt 2
tan a
=y/x
tan a = 1/1
tan a =
1
a = 45
degrees
The polar form
is:
z = sqrt 2(cos 45 + i*sin
45)
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