complex numbers question (1 Viewer)

[sadpwner]

http://imgur.com/PD7Rqs7

Why is vector QO= (0-q)i? I understand that i rotates it 90 degrees anti-clockwise, but I don't understand the (0-q) part.

 

[pdang]

its basically because if you want a vector that doesn't start at the origin you do
endpt - startpt
since its QO and not OQ, endpt is O startpt is q

 

[sadpwner]

On a similar note, is z(1)-z(2) and z(2)-z(1) the same thing? If not, what's the difference? Also could anyone mark which angles are which on the diagram and reupload the image, such as arg((z(1)-z(2))/(z(1)+z(2))? I can't find any information regarding how to identify the arguments so...

http://imgur.com/CHaHGk1