Reference dimension in diagrams?

[layton.r.miller]

I have a diagram that I want to have cut angles calculated in. I can't figure out how to create some sort of a reference axis through 2 points, as shown in the attached image. I want the angle offset, relative to the inner and outer points of that piece of the model.

I'm sure this is probably easy to do but none of my research is bearing fruit.

Thanks!

[layton.r.miller · Accepted solution]

I see it now. You have to use the angular dimension tool, as I was trying to do - however I didn't notice that you can hit "space bar" and switch it into point-selection mode. This does what I need.