The pedestrian left point A and, moving strictly northeast, covered the distance AB = S1 = 5 km in 1 hour. Then he turned east and covered another distance BC = S2 = 6 km, moving for 2 hours. After that, he went south and covered the distance CD = S3 = 6 km in 1 hour. Determine the path covered by the pedestrian in 4 hours and his displacement dr during this time (Fig.).

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