To Create a Circle
Click > 
Circle. The Snapping References dialog box opens. Use the arrow icon in the dialog box to add any references you want to set up before you sketch.
Circle. The Snapping References dialog box opens. Use the arrow icon in the dialog box to add any references you want to set up before you sketch.Choices for circles include:
• Locating its center and defining a radius point
• Making it tangent to other entities
• Locating its center and defining a point as the tangency with another entity
• Making it tangent to three other entities
• Making it tangent to two other entities, with a specified radius
• Using any three points that lie on the circle