Notes about the CG3 file extension:
To open this file type, a required software must be installed. Without it you only see a Windows message "The following file cannot be opened
" (Windows 7) or "How do you want to open this file?
" (Windows 10) if you double-click the file. There click on "More apps"
and choose a suitable software to view such files on your PC or from email attachments.
The CG3 file type is primarily associated with 'Cabri 3D' by CABRILOG SAS. Cabri 3D enables you to alleviate 3D geometry construction difficulties and also contains the benefits of interactive geometry. [The site only mentions this as a license file; the submittor listed it as a stored geometric construction so it may have multiple uses.]