Please help me solve the following sum on complex numbers:

Question

anonymous · Answer

The three roots of a complex number z (z = 2-2i) are:$$\sqrt{2}cis(\frac{ -3\pi }{ 4 }), \sqrt{2}cis(\frac{ -\pi }{ 12 }), \sqrt{2}cis(\frac{ 7\pi }{ 12 })$$

anonymous · Answer

These points (drawn on an argand diagram) represent the vertices of a triangle T (I know it's an equilateral triangle). Find the modulus and argument of each of the complex numbers which are represented by the MID-POINTS OF THE SIDES T.

anonymous · Answer

I've found the arguments, but I don't know how to find the modulus.

yttrium · Answer

Do you need this right now?
I need to out at this moment maybe I can help you tomorrow.

anonymous · Answer

ohh, no worries.

anonymous · Answer

well actually I haven't found the arguments, turns out I have no idea how to do this sum :P

.sam. · Answer

What is 'cis'

anonymous · Answer

cos x + isin x

anonymous · Answer

|dw:1378919561462:dw|

anonymous · Answer

|dw:1378919609058:dw|