I'm having some trouble figuring out if the equation z = 2 - sqrt(x^2 + y^2) is a cone, ellipsoid, or something else. If I simplify it to look like one of the forms by professor gave me, I get x^2 + y^2 - (2-z)^2 = 0, which looks like the cone formula. But if I go further it becomes ((x^2)/4) + ((y^2)/4) + ((z^2)/4) - (z/4) = 1, which makes it look like a kind of ellipsoid. Any help would be greatly appreciated and thank you in advance!