y = ax2 (xy plane)
a = coefficient
k = .25a = focus (focus to vertex)
d = twice the desired parallel or offset amount
x = x coordinate on parabola
Xc = x offset value
y = y coordinate on parabola
Yc = y offset value
Parabola Offset / Parallel Path Compensation Equations (Ref. Fig. 1)
Xc = x ± (xd / (2√(4k2+x2)))
Yc = y ± (kd / √(4k2+x2))
Fig. 1
Geogebra animation can be viewed here: Offset or “Parallel” Curve to the Parabola – GeoGebra