Worked out how to do the first part. It is a 2 step process
1. In the command bar, type POINT and select the reference point, in which case the beginning of the line
2. hit Enter for the POINT command to appear again, and this time write the relative coordinates eg @100,200
Would still like for the point to be highlighted by the cursor for locating the centre of a circle. Would appreciate it if anyone can help
Bookmarks