at (2,3,-4) express the unit vector z in spherical terms. express the unit vector r in rectangular terms. for the first part, would it just be (1,X,0) fi should be zero because thats the angle the line makes with the z axis, and since this is going to be parallel to the z-axis this should be zero and theta shouldnt matter. and the unit vector r should just be the point made into a vector right? since the unit vector r is pointing away from the origin. so at (2,3,-4) its going to be in the direction of (2,3,-4). should it have a different magnitude?