ways of expressing complex numbers
x + iy
re^iu
r(cosu+isinu)
when multiplying complex numbers
Multiply their moduli and add the arguments
|z1z2| = |z1| |z2|
arg (z1z2) =arg (z1) + arg (z2)
when dividing complex numbers
Divide their moduli and subtract their arguments
z + 1/z
2cos u
z- 1/z
2isin u
z^n + 1/z^n
2 cos nu
z^n - 1/z^n
2 isin nu