.
(c) Z1 * Z2 = (2-2i)*(-3+i) = -6 + 6i + 2i -2i^2 = -6 + 8i -2*(-1) =
= -6 + 8i + 2 = -4 + 8i.
(e) The angle (the argument) for Z1 is = -45°.
The angle (the argument) for Z2 is = 90°.
THEREFORE, the angle between Z1 and Z2 is - = .
Or, in degrees, the angle between Z1 and Z2 is 90° - (-45°) = 135°.
This answer is for minimal angle measure.
The other possible angle "between" these complex numbers is 360° - 135° = 225°,
but normally, the minimal of the two angles is considered as the answer.
---------------
On complex numbers, see introductory lessons
- Complex numbers and arithmetical operations on them
- Complex plane
- Addition and subtraction of complex numbers in complex plane
- Multiplication and division of complex numbers in complex plane
in this site.
Also, you have this free of charge online textbook on ALGEBRA-II in this site
- ALGEBRA-II - YOUR ONLINE TEXTBOOK.
The referred lessons are the part of this online textbook under the topic "Complex numbers".
Save the link to this textbook together with its description
Free of charge online textbook in ALGEBRA-II
https://www.algebra.com/algebra/homework/complex/ALGEBRA-II-YOUR-ONLINE-TEXTBOOK.lesson
into your archive and use when it is needed.