Review of Complex Number
Definition
Complex number is the combination of real number and imaginary number. It's basic form is a+bi, Where
a is the real part and bi is the imaginary part.
i is the unit for imaginary number. In a complex coordinate, a+bi is point(a,b). The distance between
this point and the origin is the square root of (a^2 + b^2).
In the form a+bi, when b=0, the complex number belongs to real number; when a=0, the complex number
belongs to imaginary number; when they both are not zero, it belongs to complex region.
The triangular form of a complex number is Z=r(cosx + isinx). r is the distance between point Z and
the origin on a complex coordiante. rcosx is real part and irsinx is the imaginary part.
Properties
- Addition: $ \,(a + bi) + (c + di) = (a + c) + (b + d)i $
- Subtraction: $ \,(a + bi) - (c + di) = (a - c) + (b - d)i $
- Multiplication: $ \,(a + bi) (c + di) = ac + bci + adi + bd i^2 = (ac - bd) + (bc + ad)i $
- Division: $ \,\frac{(a + bi)}{(c + di)} = \left({ac + bd \over c^2 + d^2}\right) + \left( {bc - ad \over c^2 + d^2} \right)i\,, $
where c and d are not both zero.
- Source for wikipedia: [[1]]
