To Draw Isometric Circles

1. Click Tools menu > Drafting Settings.
2. In the Drafting Settings dialog box, Snap and Grid tab, under Snap Type, select Isometric Snap.
3. Click OK.
4. Click Drafting tab > Draw panel > Ellipse drop-down.
5. Enter i (Isocircle).
6. Specify the center of the isocircle.
7. Specify the radius or diameter of the isocircle.