There are several groupings of three on the Enneagram, and one of these is the following set of three groupings: the optimistic triad (7, 9 and 2), the intensity triad (4, 6 and 8), and the competency triad (1, 3 and 5). Understanding the triads, along with the similarities and differences between the types in the same triad, provides useful clarity in helping to identify a person’s Enneagram type. You can also take a quiz to test your knowledge.
Books available on amazon.com
The art of typing (Lapid-Bogda 2018)