Need Help with perspective!

[Oliver Bourne]

When Mirroring a rectangle in Perspective, which corner are you meant to draw through middle with? As I get two different widths.

Am I over complicating this in my head, just cant grasp the fundamentals

[Jose A Nieto]

@Oliver-Bourne What exactly is the purpose of this? What do you want to achieve?

[Oana]

@Oliver-Bourne I am not sure I understand in the drawing wich one is the rectangle and wich is the mirroring plane, or axis?