Change the curvature of an arc
Click the Pencil tool .Select an arc or a shape that contains an arc.
Tip You can also select the arc or shape using the Pointer tool, and then position the pointer over the shape to automatically display the control point and move it.
Point to the arc's control point .Drag the control point until the arc looks the way you want.
Note An arc has an invisible snap point in the middle of an invisible line between its two endpoints. When you drag the control point (control point: (1) The circle that appears on a line segment or an arc segment when you select them with the pencil tool. Drag a control point to change the curve of an arc or ellipse. (2) A point that influences the curvature of a spline segment.) to that snap point so that the arc has no curvature, the arc becomes a line.
Change the eccentricity (or symmetry) of an arc
Click the control point on the arc to display its eccentricity handles .
On circular arcs, the eccentricity handles (eccentricity handle: The circle that appears at each end of a dotted line when a control point of an elliptical arc is selected with the pencil tool. Drag to change the angle and magnitude of an arc's eccentricity.) are under the control point.
If you don't see the eccentricity handles, hold down the CTRL key and drag the pointer slightly away from the control point.
Edit the arc by doing the following:
To change an arc's magnitude of eccentricity, drag an eccentricity handle farther from or closer to the control point. To change an arc's angle of eccentricity, drag an eccentricity handle around the control point.