Eek I haven't done 4U in a while so I might be a bit rusty but this is what I got - hopefully it's right.

https://i.imgur.com/a8xeaNY.jpg
Essentially, since it's an isosceles triangle with z

_{3} as a right angle, the remaining angles would be 45 degrees. Therefore, I think you can just manipulate the vector z

_{1} and z

_{2} by multiplying it with cis(pi/4) or cis (-pi/4) to eventually find z

_{3}.

Hopefully the working out in the image makes sense.

If I'm wrong let me know - I haven't done this in a while so I might've forgot some stuff.

Also, I believe you can have two values of z

_{3} I think - one above the real axis and one below the real axis. I'm not fully sure though.

## Bookmarks