To Create a Chain of Lines and Arcs
1. On the Sketch tab, click the arrow next to Line and then click 
Line/Arc Chain. The location of the start point is displayed, relative to the base point.
Line/Arc Chain. The location of the start point is displayed, relative to the base point.2. Select a start point for the line or arc.
3. Press S to toggle between line and arc creation mode. A line or an arc rubberbands at the pointer. The location and size of the new entity is indicated.
4. Select a second point to size the line or arc.
5. To lock the dimensions of the entity you are creating, press Enter. Press Tab to switch to the other dimensions.
6. Repeat steps 3-4 as needed.
7. Middle-click aborts the rubberband.