Ok, I've been trying to work this out for a couple of hours now and I'm completely stumped. Not even Google was helping much. The question is: Find and Sketch the level curves of the scalar field T(x,y) = (x +y)/(x2 + y2) for T = -1, -0.5, 0, 0.5, 1 I know that I should equate the equation to the values of T given and I suspect that I'll be getting 4 circles but it doesn't seem to work. Here's what I've done: (x +y)/(x2 + y2) = -1 x + y = -(x2 + y2) Where do I go from here?!