How do the dipped headlights illuminate the road in front of a passengers car?

Why?

In a car designed for right-hand traffic, dipped headlights illuminate the road asymmetrically, reaching farther on the right. The beam is restricted on the left to avoid dazzling oncoming drivers. “Symmetrically” ignores this difference, while “perpendicularly” does not describe the correct light distribution. The photograph shows the right-hand road edge and oncoming vehicles, but not the beam pattern itself.