To Create a Line
1. On the Sketch tab, click the arrow next to Line and then choose a creation method:
◦ Click 
Single and select the start point of the line.
Single and select the start point of the line.◦ Click 
Tangent and select an arc or circle at the point of tangency to set the start point of the line.
Tangent and select an arc or circle at the point of tangency to set the start point of the line.When you select a creation method, the location of the start point is displayed, relative to the base point.
2. Rubberband the pointer and select a second point to size the line.
 | Use the dimensions mini toolbar to change references or change dimension types. |
3. To lock the dimensions of the entity you are creating, press Enter. Press Tab to switch to the other dimensions.
4. When creating a line chain, continue selecting more points as needed.
5. Middle-click aborts the current rubberbanding.