1. The problem statement, all variables and given/known data Let C be a straight path from (0,0) to (5,5) and let F=(y-x+2)i + (sin(y-x)+2)j. At each point of C, what angle does F make with a tangent vector to C ? 3. The attempt at a solution Well the displacement vector for C going from (0,0) to (5,5) is simply C=5i+5j. The tangent vector to this would be parallel to this vector, since C is a straight line. So my tangent vector is also 5i+5j. (Does this make sense?) Now to find the angle between F and C, i chose to do a dot product between them. The dot product yields following result. F.C = 5y-5x+5sin(y-x). Since y=x in the displacement vector C, can i simply say that y=x, so the dot product is zero. Therefore the tangent vector and F vector are perpendicular to each other. Thanks in advance.