A hiker walks 3.70 m, N and 11.58 m, E. What is the magnitude of his resultant displacement?

i had this question and the answer was 3.15 miles.

martina travels from school to her mom's office. from there, she walks to school. after school, she walks to the library and then to a friends house before finally ending back at home. find martina's total distance traveled.

a) 0 miles  

b) 0.4 miles  

c) 1 mile  

d) 3.15 miles

answer; how far out of place which the object finished relative to the starting location;