I am currently doing an online self learn course and seem to have come to a bump in the exercises.
Here is the question.
Indicate if the statement is True or False. If true prove it, if false give a counter example.
arg z1z2 = arg z1 + arg z2 if z1,z2 is not equal to 0.
I have never encountered 'arg' before and have no idea what to make of it. I am currently googling away but some explanation would be helpful. No need to help me solve this, just an explanation of what 'arg z1z2' is would mean a lot!. I can't even find any reference to this in the given book or study guide.