If your design includes rounded corners, use the FILLET command. To issue FILLET, you choose FILLET from the Modify pull-down menu or toolbar. With FILLET, you not only create rounded corners between two lines, rays, xlines, or line segments of a polyline, but also draw an arc segment between any combination of two lines, rays, xlines, circles, ellipses, arcs, elliptical arcs, or splines. The generated arc is always drawn so that it starts and ends tangent to the two selected objects.
Creating an Arc Using FILLET
To draw the arc, you first use the Radius option to set the radius, then you select the two objects. As with CHAMFER, if the two objects are nonparallel lines, the lines are trimmed or extended to a corner point, ...