The Unit Circle
The unit circle is just a circle with radius one. Therefore every vector that has its endpoint on the unit circle and has its origin in '0 + 0j = O' has of course also a length of one.
In some respects this makes calculations a little easier because on the unit circle the imaginary axe (say the Y axe) is the sine of the angle of the vector and the real axe the cosine of the angle. Since the subtendent side of the right angle is one and
a2 + b2 = c2
which will be shown in a following paragraph.
We can then, sort of, split the vector in two components. One has the angle information and one has the length information.
Z = |Z| ( cos( a ) + j sin( a ) )
|Z| is here the absolute value, i.e. the length, of the vector. While the length of 'cos( a ) + j sin( a )' is exactly '1' but has an angle of a.
However sometimes its easier to use sine and cosine and sometimes we just use te vectors themselves. The first we have to do is deduct an important formula we will use. Then we will use this formula to see what happens when we perform the different functions on the vectors.