"Plain" 3d arc/circles imported from DWG/DXF are recognized as such in the SKP, so you can then change their segmentation in Entity Info later [there is also a script to change selected arc/circle's segmentation en mas sin the same way]. If the arc is part of a 3d form it's not changeable.

Thanks for the information. Yes indeed in the file menu i can import dxf and dwg files but i have still a problem left. When i for example draw a circle in autocad, save it and then import it in sketchup (even when i have already a component in the scene)the circle apears in the scene but there is no surface created such as when you draw a circle in SU. My intention was to draw complex sections in autocad and then export them to SU to make 3D models of it with for example the push/pull function.

Align Tools 3D by Didier Bur
Component onto face by Chris Fullmer 😉

Look in the 'Tools' menu for 'Angular dimension'...
Not every loaded script shows an entry under the 'Plugins' menu...
You can often find in which menu a tool will appear by opening its .rb file in a plain text-editor [like Notepad.exe] and looking for the menu code, which is usually near the end of the text - it's usually clear where it shows and what it's called... That's what I just did to tell you where to look... 😉