One afternoon, a postman drives 3.50 km due west of the post-office to deliver an express package in a house. He then walks due north to a coffee shop to meet a group of pensioners. If the magnitude of the postman's total displacement vector at the coffee shop with respect to the post-office is 3.55 km,
a) How far north the postman walked?
b) What is the direction and angle of his total displacement vector while at the coffee store with respect to the post-office?
