Menu: Draw / Ellipse / Center 
Creates an ellipse by its centerpoint, major axis and minor axis.
- Select the centerpoint of the ellipse.
- Move the mouse to set the length and angle of the major axis, or enter the major axis length and angle in the Inspector Bar.
- Set the length of the minor axis, which is always perpendicular to the major axis. You can also enter the axis length in the Inspector Bar.
Local menu option: Rotation: 
Sets the minor axis by rotation from the horizontal axis, rather than perpendicular from the major axis.