How does one find the argument of the complex number: (1/(9x*i)). As I understand that this equates to: arctan(1)-arctan(Im{9x*i}/Re{9x*i}) but that's undefined?

Question

phi · Answer

what do we know about x?  is it a pure real ?

anonymous · Answer

Sorry, x is real and greater than zero.

phi · Answer

so 9xi is on the imaginary axis (y-axis), and its angle (argument) is pi/2

anonymous · Answer

Ah, of course :) Thank you!

phi · Answer

and you really want atan( Im(1)/Re(1))  not atan(1).  
But 1 is pure real, and its angle is 0