Question: i have provided a worked out solution of the problem...

I have provided a worked out solution of the problem on the second picture. I would like to know a much more detailed answer, specially when doing the conversion of Z_2 from polar to Cartesian notation (please explain me why the "x" is positive and the "y" negative on its Cartesian notation). I would also like you to specially detail me the conversion of Z_3 to Polar.

If you help me with my request I will rate max. :)