Figure 8. I've never went that far. Chain works for lines only. It copies or traces the edge of an existing element on which it is clicked see Figure 13.
This tool generates a smooth curve see Figure 8, A by clicking a series of control points. If you enter an angle value in the Options Bar and press [enter], Revit will rotate the element directly.
I know the two chars shortcut is better, but it worth to try. Figure 3. We click the start point, then define the end point.
Figure 14. This tool creates a curve from the end point of an existing line or curve. See Moving Lines and Components with Walls.
The section would ideally cut perpendicularly through each unit, but since each unit is oriented to the site and slightly at an angle relative to each other the building sections don't read very well with Revit's straight-line section cut. You may end up with conflicting constraints or endless loops. To refresh your memory, you can see the wall layers definition in wall properties.
This tool creates a line or curve based on an existing edge. Creating a fillet arc. The radius of the arc can be edited by entering a value over the temporary dimensions see Figure 9, A or dragging the middle drag control see Figure 9, B.
They have different concept. Make sense?
Figure 1. This tool creates a circle by clicking two points. In sketch mode, they enable sketching and placing of profile elements quickly and accurately.
The angle between these two points determines the rotation.