Drawing Elliptical Arcs and Full Ellipses

To draw an elliptical arc or a full ellipse, choose the Arc/Circle tool in the Toolbox and one of the Geometry Methods offered by the second icon in the Info Box (Diagonal Ellipse, Semi-Diagonal Ellipse, Ellipse Radii).
The Diagonal Ellipse method creates an Ellipse constrained into a rectangle.
This method stretches the ellipse of an invisible rectangle held by the two points of its diagonal.
1.
Click the starting point of the imaginary rectangle.
2.
By stretching the imaginary diagonal, you get ellipses of different sizes drawn into the invisible rectangle.
3.
With the second click you choose the ellipse of the appropriate size.
The Semi-Diagonal Ellipse method works in the same way as the Diagonal method but here you define the imaginary rectangle by its centerpoint and the endpoint of its semi-diagonal.
The Ellipse Radii method defines an elliptical arc by the major and another radius of an ellipse and the angle of the arc.
                          
1.
Click the centerpoint of the ellipse.
2.
Choose the orientation of the major radius, by clicking again.
3.
You get the rubber band line of the second radius, which you can stretch to different sizes and angles. Notice the accompanying ellipse that fits the length of the two radii. If you stretch the minor radius too far away or right in line with the major radius, you cannot draw the ellipse.
4.
In the final phase, ARCHICAD holds the ellipse while you define the side angle of the arc. First, you use a rubber band line to define the side where the angle starts from. Then you define a different side that closes the angle, while ARCHICAD follows the angle with the Elliptical Arc. Neither side of the angle remains visible when the final arc is drawn.