Euler’s circle :  In geometry, the nine-point circle is a circle that can be constructed for any given triangle. It is so named because it passes through nine significant concyclic points defined from the triangle. These nine points are:

The nine-point circle is also known as Feuerbach’s circleEuler’s circleTerquem’s circle, the six-points circle, the twelve-points circle, the n-point circle, themedioscribed circle, the mid circle or the circum-midcircle (wikipédia)

I find signs everywhere… I see that 9 in an inverted 6, it is the symbol of the end AND of the beginning… And my story begin in 1969, etc.