the velocity of a car?

Question

If car A is traveling at 50 km/hr at an angle of 10 degrees east of north and car B is traveling at 70 km/hr at an angle of 30 degrees south of east, what is the velocity of car A at seen by car B?

Answer 1

A(east) = 70 sin 10 = 12
A(north) = 70 cos 10 = 69

B(east) = 70 cos 30 = 61
B(south) = 70 sin 30 = 69

A relative to B is
west travel at 61 - 12 = 49 and
north travel at 69 + 69 = 138

These vectors combined are magnitude 146 (by the Pythagorean Theorem) with angle of invcos(49/146) = 70 degrees west of north.