[b]LARGE POINTS[/b] are moveable. [br]The points along the curve stay within the plane containing the grid. [br]To move the [b]dashed line[/b], move any of the 2 points that lie on it. [br][br]Move the [b][color=#a64d79]LARGE POINT[/color][/b] (with arrow(s) attached) UP and DOWN to spin the curve about the dashed line. Doing so will form the 3D surface of revolution with this curve serving as its cross section. [br][img width=230,height=230]https://lh3.googleusercontent.com/y_V1JhZqfb2orp4Eo9ZbvTuC1G1p8i8XHxf9gvMOxqH95R3cSGC80DmfdyMbcspWL4vjLogH5E3z6pfR-TkNx_T00TPwJuty5l3YbUUdSoIeAFjkOulRIItrkfKeykwuG3EYjQoW[/img]