Checking angle of drafted walls?

Can someone tell me how to check the angle of a drafted wall? How do I check it in reference to a vertical or horizontal line? I try using the “Angle” dimension under the “Evaluate” tab but all I ever get is either 90 degrees (Which it is not) or an error that say “Parallel lines can not create angle dimensions”. I had a trainer on site here a while back and he couldn’t answer it for me either. Can anyone offer any suggestions?

Thanks.

You mean an example like that?
obrázek_2024-05-17_111921153