It's true. First day of class he branded himself as a "learning assistor" and he wasn't kididng. He literally doesn't teach and requires us to read the book and learn it on our own. I have a test tomorrow, and I don't have a textbook (problems with ebay) but I do have review sheets so I have a few questions: Magnitude: What is the formula for calculating it? Given that a force extends from the origin to (120 N, -60 N) find the magnitude of the vector. Ok well to be honest, I have no idea how to do this problem :D I think you draw a graph and then draw the vector between 120, -60? Here's another one: Vector A has a magnitude of 3.0 units and makes an angle of -90.0 with the positive x-axis, vector B has a magnitude of 4.0 units and makes an angle of -120 with the positive x-axis. What is the direction of the vector sum of A+B referenced to the positive x-axis? I think the wording confuses me here. I know to draw a graph, and vector A is on the y-axis going downward (negative) and is 3 uints long. Vector B, I'm not sure which way to draw it... does it go in quadrant III or IV? Anyway, because i know its 120 degrees, that means the intersection o fA and B is 30 degrees.. but I'm not sure what hte problem means by what is the direction of the vector sum..... Any help would be much appreciated.