The Sun is always at the back of your head/eyes with the rainbow directly in front of your eyes. Therefore the rainbow is always west (mornings), north (day) or east (afternoon) (for the northern hemisphere). Which means no two or more people can see the same rainbow!
Just as the relationship of hypotenuse of face/base to centre of the Great Pyramid is Phi/1 (angle of face is 51.82729237). Which is the angle of incidence of the secondary rainbow often observed in the aftermath of large storms.
Primary Arc: 40° - 42°
Secondary Arc: 52° 15'