CADarc (by radius)
To create arcs by radius, select the CAD Arc (by radius) tool and position the cursor where you want the center of the arc. Click the mouse button once and release it. Then position the cursor where you want the arc to begin - which is the arc radius. Click and drag counterclockwise to create the arc. Hold down the control key to create the opposite angle.

CADarc (by points)
To create arcs by points, select the CAD Arc (by points) tool and position the cursor where you want the arc to begin. Click the mouse button once and release it. Then position the cursor where you want the arc to end. Click and drag back and forth to adjust the size of the arc. Hold down the control key to create the opposite arc.