Are yams and sweet potatoes the same?
an open surface generated by rotating a parabola (q.v.) about its axis. If the axis of the surface is the z axis and the vertex is at the origin, the intersections of the surface with planes parallel to the xz and yz planes are parabolas (see , top). The intersections of the surface with planes parallel to and above the xy plane are circles. The general equation for this type of paraboloid is x2/a2 + y2/b2 = z