Choose the Arc By 3 Points command 
.
Click where you want the sweep of the arc to begin (A).
Do one of the following:
Click where you want the midpoint of the arc to be (B), and then click where you want the sweep of the arc to end (C).
Click where you want the sweep of the arc to end (B), and then click where you want the midpoint of the arc to be (C).
Tip:
Use the intent zones at the first and second points to specify whether the third point is between the first two or beyond one of the first two.
Tip:
Instead of clicking to define the sweep and the midpoint, you can type values on the Arc command bar. You can also use a combination of graphic and command bar input.
IntelliSketch places relationship handles.
You can use the options on the Arc command bar and the commands on the shortcut menu to edit an arc.