Detailed Drawings > Working with Drawing Sketches > Sketching in Drawing > To Create an Arc
  
To Create an Arc
Click Sketch > Arc. 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. You can also create an arc by doing the following:
Selecting an endpoint that is tangent to another open entity (that is, not a circle or an ellipse)
Selecting any three points that lie on the arc
Using the arc center and two endpoints
Using the arc center, a start point, and an angle that strokes the arc from the start point in a counterclockwise direction
Making it tangent to three other entities
Making it tangent to two other entities, with a specified radius