Probably a stupid question, but I am making it up as I go along here. I'm putting trim on a project I'm doing. I have a square base that I'm putting trim around. One of the corners has been cut off, so there are three 90°angles. I can't figure out how to cut the trim for the section of the base that I cut off. The two pieces of trim that I'm trying to connect were originally 45°, but I cut them off thinking that would help. I'm sure I screwed that up. Help!