Conic curves are formed when a cone is intersected by a plane. As shown in the following diagram, when a plane not parallel to the base of a cone cuts it in a specific way, an ellipse is made. An example of an ellipse in the real world is the path of planets around the sun:
Figure 3.30: The conic curves made by intersecting cones along different planes
There are two ways of making an ellipse in AutoCAD. You can make it with a center and an endpoint or with endpoints of the axes. Both the ellipse commands are in the Draw panel in the Home tab under the ellipse flyout, as shown:
Figure 3.31: The Center and Axis, End ellipse options in the Draw panel
To make a center ellipse, select the Center option from the ellipse flyout in the Draw panel:
Figure 3.32: The A ellipse is made with the Center ellipse option and the B ellipse is made with the Axis, End option...