Mathematics Database Programming Web Design Price List     Complex analysis studies the most unexpected, surprising, even paradoxical ideas in mathematics. The familiar rules of math of real numbers may break down when applied to complex numbers. Free Lessons Lesson 1 Complex numbers In this lesson: Forms and representations of the complex numbers; Modulus and arguments; Principal value of the argument. Lesson 2 Trigonometric and algebraic form conversion In this lesson: Complex numbers forms conversion; Examples of the conversion. Lesson 3 The algebra of complex numbers In this lesson: Arithmetic operations with complex numbers; Properties of the complex numbers; Geometric interpretation of addition & subtraction. Lesson 4 Geometric interpretation of multiplication In this lesson: The modulus and argument of the product; Multiplication of complex numbers as stretching - squeezing and rotation; Multiplying a complex number by imaginary unit i and by powers of i. Lesson 5 Division of the complex numbers In this lesson: Definition and notation of conjugates and reciprocals; Division as multiplication and reciprocation. Lesson 6 Powers and roots of complex numbers In this lesson: De Moire's theorem; Powers of complex numbers; n-th root of complex numbers. Lesson 7 Complex Exponential Function and Complex Logarithm Function In this lesson: Definition and notation; Complex logarithm function is a multi-valued function; Principal branch of the logarithm. Lesson 8 Complex Trigonometric Functions and Complex Inverse Trigonometric Functions In this lesson: A difference between the real and complex trigonometric functions; Relationship to exponential function; Identities; Derivatives and Indefinite integrals of inverse trigonometric functions. Lesson 9 Complex Hyperbolic Functions and Inverse Hyperbolic Functions In this lesson: The notations; Definitions; Derivatives and Indefinite integrals of inverse hyperbolic functions. Lesson 10 Complex Power Function In this lesson: Raising a complex number to a complex power; Derivatives and Indefinite integral of complex power function. Lesson 11 Complex Rational Functions In this lesson: Definition of the rational function; Möbius transformations; Fractional-linear function; Zhukovskii function. Complex numbers. Examples of the conversion from algebraic to trigonometric form Complex Analysis. FreeTutorial

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Formulas of the conversion from algebraic to trigonometric form

Formulas of the conversion from algebraic to trigonometric form of the complex number

The conversion from algebraic to trigonometric form of the complex number is given by
|z| = , (1.7)

If z is purely imaginary number, then x = 0, and becomes undefined. We emphasize these special cases: (1.8)
If y = 0, then z becomes a real number. (1.9)

arg(z) is indeterminate if x = 0, y = 0.

Examples of the conversion from algebraic to trigonometric form

Example 4:
Algebraic form of z :
z = 2 + 2 i.
What is the trigonometric form of z ?
z = |z|{cos Arg(z) +i sin Arg(z)} .
|z| = = 4.
arg
(z) = because x>0. See (1.7)
The principal value arg(z) = arctan = .

Trigonometric form:
z = 4(cos + i sin ).
Arg(z) = arg(z) + n = + n.
z = 4(cos( + n) + i sin( + n)).

Example 5:
Algebraic form of z :
z = -1 + i.
What is the trigonometric form of z ?
z = |z|{cos arg(z) +i sin arg(z)} .
|z| = = 2.
arg
(z) = + because y>0. See (1.7)
arg(z) = - + = Trigonometric form:
z = 2(cos + i sin ).

Example 6:
Algebraic form of z :
z = - i.
What is the trigonometric form of z ?
z = |z|{cos arg(z) +i sin arg(z)} .
|z| = = 2.
arg(z) = because x>0. See (1.7)
arg(z) = = .
z = 2(cos( ) + i sin( )).

Example 7:
z = -i
What is the trigonometric form of z?
z = |z|(cos arg(z) +i sin arg(z)).
|z| = = 1
arg(z) = because x = 0, y <0.

z = cos( ) + i sin( )

Example 8:
Algebraic form of z :
z = -5 - 3i.
What is the trigonometric form of z ?
z = |z|{cos arg(z) +i sin arg(z)}.
|z| = = .
arg
(z) = - because x<0, y<0. See (1.7)
arg(z) = Trigonometric form:
z = (cos( ) + i sin( )).

Example 9:
This example is more complicated.
Write a number z = -sin + i cos in a form
z
= |z|{cos arg(z) +i sin arg(z)}.

|z| = = = 1.
arg(z) = + because x<0, y>0. See (1.7)

 x = - sin ; y = cos ;

arg(z) = arctan{cos( )/(-sin( )} + = + = .
z = cos +i sin .

We can get the same result geometrically. Let us represent 2 points in the complex plain:
a given point z = -sin + i cos ,
and a point z1 = cos + i sin .
It is clear that arg(z) =  = ,
so z = cos +i sin . Figure 1.5 Example z = -sin + i cos Previous theme Content Next theme

by Tetyana Butler Top  Possibly the greatest paradox is that mathematics has paradoxes... Bernoulli's sophism Paradox of Bernoulli and Leibniz Paradox of even (odd) and natural numbers Paradox of Hilbert’s hotel Ross-Littlewood paradox Paradox of wizard and mermaid Paradox of enchantress and witch Paradox of Tristram Shandy Barber paradox Achilles and tortoise Contact us