The calculated distance (air line) between Cergy-Pontoise and Triel-sur-Seine is approximately 5 miles respectively 9 kilometers.
By car or train, the actual journey to Triel-sur-Seine is certainly longer, as only the direct route (as the crow flies) between Cergy-Pontoise and Triel-sur-Seine has been calculated here.
Air line (approximately)
9 kilometers
5 nautical miles