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
DescriptionE6-roots-of-E8.svg
English: Roots of E6 derived from the split real even roots of E8, specifically those that are perpendicular (the same) in the last three dimensions. Shown with the full E8 root with 8D norm length of Sqrt(2).
to share – to copy, distribute and transmit the work
to remix – to adapt the work
Under the following conditions:
attribution – You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.
share alike – If you remix, transform, or build upon the material, you must distribute your contributions under the same or compatible license as the original.