Graph sketching, and easy approach?

[Master J]

I have been given a multivariable function.

Now to sketch it, I could plug in some arbitrary values and plot it out, but is there an easier way?

How exactly can I figure out the sketch of a graph?

F(x,y) = (c - x^2 - y^2)^(1/2), c is a constant

 

[Dick]

One way is to think about the level surfaces of f(x,y). I.e. pick a constant K and figure out what the graph of f(x,y)=K looks like as a curve in the x-y plane.