I will be philosophical here...
A square is 4 -90degree angles (definition of perpendicular lines)
If we create a diagonal it splits it into two triangles which in result gives us
90degree + 90/2 degree+ 90/2 degree (because the diagonal split it in half and one full 90 by definition of perpendicular lines)
That gives us the beautiful 180 degrees
which is also what humans use to say that they’ve completely changed or did something completely different...
Mysteries of the triangle...
Six six six six six six