Part 1

In the app below, [b]LARGE POINTS[/b] are moveable. [br][list][*]You can change the shape of the curve and the dashed line by moving any one (or more) of these points.[/*][*]Move the[b][color=#ff00ff] LARGE COLORED POINT [/color][/b](with arrow) UP to create a 3D surface. [/*][/list]
What kind(s) of surfaces were you able to make this way? What do they look like?

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