Level Surface

If a function w = f (x,y,z) is assigned to a value c, i.e. f (x,y,z) = c, then the surface f (x,y,z) = c is named as the level surface of f. 

There are two functions given in the box below: f (x,y,z) and g(x,y,z). By default, f (x,y,z) = 1 is shown. Tick on other choices of c from the same function to observe the changes on the level suface. You may click here if you want to rotate the graph.

Betty, created with GeoGebra and Thomas' Calculus, Pearson.