Constrain line or ellipse to be collinear

The collinear constraint causes selected lines or ellipse axes to lie on the same line.

1. On the ribbon, click Sketch tab Constrain panel Collinear Constraint .
2. Click the first line or ellipse axis.
3. Click a second line or ellipse axis.
4. Continue to place collinear constraints, or do one of the following to quit:
   • Right-click, and select Done.
   • Press Esc.
   • Select another command.

Show Me how to create a collinear constraint