Every circle and every ellipse is constructed from a certain number of polygon lines. The number of segments can be defined in the dialog box for this menu item.
A minimum of 3 segments can be defined. A triangle would be drawn in this case. Defining a start angle is then practical, because this influences the orientation of the triangle.
In addition, the centre of the circle or ellipse can be provided with a cross, the size of which can be specified here.