Using PolarSnap
To turn on PolarSnap
- From the Tools menu, choose Polar Snap Settings.
- In the Ortho/Polar dialog box, choose On.
- Select the PolarSnap option you want to use.
- If you are using an angle snap, specify the angle to use.
- If you are using a distance snap, specify the distance to use.
- If you want to use distance and angle tooltips, select ToolTips.
- Choose OK.
Standard toolbar: 
Command line equivalent: POLAR