We are given Z, and are asked to find the magnitude of the expression. See attached picture(s)
See attached pictures(s)
The Attempt at a Solution
When I solved it on the exam, I did it the long way using De Moivre's theorem. I ended up making a few sign errors which cost me points. When my professor went over the exam, he did the problem as shown on the second picture with the purple pen writing. What I am wondering is why you can solve it this way? Why in the denominator you can just multiple the magnitude of both terms without having to evaluate it?