A plane flew due north at 500 miles per hour for 3 hours. A second plane, starting at the same point and at the same time, flew southeast at an angle clockwise from due north at 435 miles per hour for 3 hours. At the end of the 3 hours, how far apart were the two planes? Round to the nearest mile.

A plane flew due north at 500 miles per hour for 3 hours. A second plane, starting at the same point and at the same time, flew southeast at an angle clockwise from due north at 435 miles per hour for 3 hours. At the end of the 3 hours, how far apart were the two planes? Round to the nearest mile.