Logarithm of a Complex number question?

[Mandynash]

Homework Statement

The question is located here http://i51.tinypic.com/2cge9mt.jpg

Homework Equations

My a value is -3
my b value is -3sqrt(2)
my c value is -2.4

The Attempt at a Solution

1) ln(-3 - 3 sqrt(2) i)
= Ln |-3 - 3 sqrt(2) i| + i arg(-3 - 3 sqrt(2) i)
= ln sqrt(27) + i (-3π/4 + 2πk), for any integer k

2) ln(-c) = Ln |-c| + arg(-c) = ln c + i(π + 2πk) for any integer k.

(Principal value occurs for k = 0.)


Managed to get this far but I have no idea what I need to do next! Thanks in advance for the help.

 

[dextercioby]

For 2) you just have to plug c=2.4.

For 1) you may want to check the angle again. I get \arccos\left(-\frac{\sqrt{3}}{3}\right)