Can someone give me direction on where to begin with parameterizing the function of f(x,y) = x^2+y^2-x-y. I know that x = r cos t, y = sin t and r = z. the shape of this function is a paraboloid. I believe that the function in the x-y planes would be a circle. that being said, I think I can say (cos t, sin t, ?t^2?). Any help or direction would be greatful.