It would be good to provide a tool to draw curved lines (arcs of circles and / or ellipses) as we can draw straight lines .
This tool may permit configure arrows styles, lines styles, color and the others options available.
This tool can use the same procedure to draw an arc of ellipse or an arc of circle, making the half major axis equals to the half minor axis to draw a circle.
The tool exists in Draw and Impress, but you have to customize the drawing toolbar. Right-click toolbar > customize toolbar > Add… Find the command “Ellipse” (that with ‘toolbar’ in its description) in the category “Drawing”. Or goto menu View > Toolbars and open the separate toolbar “Circles and Ovals”.
There is no preconfigured grouping toolbar in Writer or Calc, but you need to set the single commands to “visible” in the customize toolbar dialog.