The calculated distance (air line) between Roßlau and Treuenbrietzen is approximately 31 miles respectively 49 kilometers.
By car or train, the actual journey to Treuenbrietzen is certainly longer, as only the direct route (as the crow flies) between Roßlau and Treuenbrietzen has been calculated here.
Air line (approximately)
49 kilometers
26 nautical miles