Calculating the magnitude of displacement

[microlab]

A car us driven at a velocity of 72km/h EAST for 0.50hr, 48km/h NORTH for 0.25hr, and 62km/h WEST for 0.50hr. Calculate the magnitude of its displacement.

Attempt at the solution:

Distance = Speed * Time

(72 x 0.5) + (48 x 0.25) - (62 x 0.5) = 17km

However, the answer in the book says 13km and I can't figure out how..

 

[Muphrid]

If you go 1 km north and 1 km east, you're not 2 km away from where you started; you're about 1.4 km away. This is the quantity you're being asked for. What do you know about the pythagorean theorem?

 

[microlab]

Oh okay, I get it.. So i have to get the difference of the East and West vectors and use pythagorean theorem to find the resultant vector.