Agirl attempts to swim directly across a stream 15 meters wide. when she reaches the other side, she is 15 meters dowstream. calculate the magnitude of her displacement

Thank you for posting your question here at . The distance downstream is one leg, the width of the stream is the other. So the displacement is the hypotenuse. Below is the solution:

15^2 + 15^2 = c^2 
450 = c^2 
21.21 meters