This command extends an arc entity.
Pick arc to extend: select an arc entity
Break Arc at Extension [Yes/<No>]? N Answering
Yes will create a new arc starting at the end of the
existing arc.
Enter or pick the distance to extend: 5 This extends
the arc 5 units
Enter or pick the distance to extend ('U' to Undo): press
Enter to end
Pulldown Menu Location: Edit > Extend
Keyboard Command: extarc
Prerequisite: An arc