Their running paths form the legs of an isosceles right triangle. The hypotenuse of such a triangle (the distance between Steve and Scott) is √2 times the length of one leg. Each has run 10 miles in the hour since they split.
ABCD is a trapezium. Since line AB and CD do not vary in y, they are parallel. Lines AD and BC are not parallel, as AD increases in x, and BC decreases in x. A quadrilateral with only one set of parallel lines is a trapezium
