This file is from Wikimedia Commons and may be used by other projects.
The description on its file description page there is shown below.
Summary
This image was uploadedas GIF, while a different format would have been more suitable. Commons discourages the use of GIF files, except for animations. See Commons:File types for more information. If possible, please upload a PNG version (or JPEG for some photos) of this image, and mark the GIF image as {{Superseded|‹new image name›}}. If you like, encourage other Wikimedia projects using the GIF to use the new version instead. If this image is a diagram or other image suitable for vectorisation, please tag this image with {{Convert to SVG}} instead of {{BadGIF}}. If not suitable for vectorisation, use {{Convert to PNG}}. For more information, see {{BadGIF}}.
This image of simple geometry is ineligible for copyright and therefore in the public domain, because it consists entirely of information that is common property and contains no original authorship.
Original upload log
The original description page was here. All following user names refer to meta.wikimedia.