Sorry if this comes to abrupt, but does anyone have a lisp that will get the Theoretical/Virtual sharp as seen on the figure above. We used to have this in AutoCad that when I click line a and line b it will automatically create the virtual corner. I'm not even sure it that's the right term for it. If not can someone please tell me where can I search for this lisp? searching online is a bit overwhelming for me and its not quite what I'm looking. Thanks in advance