A Runaway Dog Walks 0

Multiple Choice

A runaway dog walks 0.64 km due north. He then runs due west to a hot dog stand. If the magnitude of the dog's total displacement vector is 0.91 km, what is the magnitude of the dog's displacement vector in the due west direction?

A) 0.27 km
B) 0.33 km
C) 0.41 km
D) 0.52 km
E) 0.65 km