Hi

Take this question: A velocity vector is described as 400 km/hr in a direction of 150 degrees (i.e., 30 degrees north of west). Separate this into its north and west vectors.

I know this is hard without a diagram, but to do this I made a right angled triangle from the vector with 400 as the hypotenuse and the right angle 'at the top right' between north and west. I took the angle between the north vector and the hypotenuse as 60 (150-90) and did:

cos(60) = adj (VNorth)/hyp =

cos(60) = VNorth/ 400 = 200km/hr

The solution on the website was Vnorth = sine(150) * 400. There is no diagram. I don't understand how you could make a right angled triangle with the north vector the opposite side to a 150 degree angle.

In this case you get the same answer but in other examples on the same site they get a different answer to me using their approach. The quesiton is actually q1 on this page about the plane

http://www.physicsclassroom.com/Class/vectors/U3l1g.cfm
thankls