The 8 rowers in the racing boat stroke so that the angles formed by their oars with the side of the boat all stay equal. Explain why their oars on either side of the boat remain parallel.

Answer 1

Use the corresponding angles converse:

If two lines are cut by a transversal and the corresponding angles are congruent, the lines are parallel.

The transversal line is along the side of the ship parallel to the water, and the angles of the oars with the water are all corresponding angles with respect to this line

Answer 2

The rowers keep corresponding angles congruent