1. The problem statement, all variables and given/known data Basically I have two problems that are asking for the partial derivative with respect to x and y at a certain point on a level curve graph, and a contour map. How do you go about doing these? There is no function given, so I don't really know what they expect you to do. Theres also no examples at all in my book or from lecture notes. 2. Relevant equations 3. The attempt at a solution So I know to leave y as a constant if im differentiating with respect to x and etc...but I just don't know how to calculate a tangent line in these situations. Any help/hints appreciated.