Level Sets Math Insight
A level curve of a function of two variables is completely analogous to a contour line on a topographical map (a) A topographical map of Devil's Tower, Wyoming Lines that are close together indicate very steep terrainFigure 16 shows both sets of level curves on a single graph We are interested in those points where two level curves are tangent—but there are many such points, in fact an infinite number, as we've only shown a few of the level curves
