Achild and her mother are at the park. the child walks around the rectangular park while her mom waits on a bench. the child returns to the bench, finishing her walk at the same place she started. the park is 411 meters wide and 475 meters long. what was the displacement of the child?

The child covered a total distance equal to the perimeter of the park. 
That's double the sum of its length and its width . . . 1,772 meters.

However, 'displacement' is defined as the distance and direction from
the start-point to the end-point, regardless of the route followed.  Since
the child finished her walk at the same place from which she started it,
her displacement was zero.