Use the Sketch Solving Status
This is a quick way to analyze a sketch and detect whether it is under-constrained or over-constrained.
- Select all the circles.
- From the Sketch section of the action bar, click Constraints Defined in Dialog Box 
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- In the Constraint Definition dialog box, select the Fix check box, and then click OK.The geometry color turns to green indicating that the view geometries are iso-constrained.
- Select the two vertical parallel lines.
- Click Constraints Defined in Dialog Box  and select the Fix and the Vertical check boxes.The geometry color turns to green indicating that the view geometries are iso-constrained. and select the Fix and the Vertical check boxes.The geometry color turns to green indicating that the view geometries are iso-constrained. 
 
- Click OK.
- From the customized section of the action bar, click Sketch Solving Status
			 . .For more information, see Customizing an Action Bar by Adding Commands. This command gives you a quick diagnosis of the geometry status. The Sketch Solving Status dialog box appears and informs you of the general geometry status, whether it is under-constrained, over-constrained or iso-constrained. Meanwhile, the information given in the Sketch Solving Status dialog box is highlighted in the work area and the element that are under-constrained are highlighted too. In this case the four points are highlighted indicating that they are under-constrained.  
 
 
					
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