In the applet below,[color=#ff00ff] [b]both spheres[/b][/color] you see are tangent to the [b][color=#bf9000]cone[/color][/b] and are also tangent to the [b][color=#38761d]plane[/color][/b].[br]These spheres are called Dandelin Spheres (in honor of Belgian mathematician Germinal Pierre Dandelin). [br][br]The [b][color=#1e84cc]point[/color][/b] at which [b][color=#ff00ff]each sphere[/color][/b] is tangent to the [b][color=#38761d]plane[/color][/b] is [b][color=#1e84cc]shown in blue.[/color][/b] [br][br]The cross section of the plane and cone is shown. [br][b]What does this particular cross section look like?[/b] [br]How does the action displayed (by sliding the slider) help illustrate this? [br][br]Feel free to move any of the [b]LARGE POINTS[/b] anywhere you like! [br]Yet for this case, make sure that you see BOTH spheres at all times. [br][br]What would need to happen in order for the conic section to change into another particular conic section? Explain. [br][br][color=#1e84cc][b]To explore in Augmented Reality, see the directions below this applet. [/b][/color][br]

1) Open up GeoGebra 3D app on your device.[br][br]2) Go to MENU (upper left corner). [br] Go to OPEN. Under Search, type vfGNeMqJ [br] Find the slider named w and slide it slowly.