If you want to create a cone or cylinder by spinning a 2-dimensional shape about an axis symmetry, what shapes would you need to use, and why?

I have for a cone use a triangle and for a cylinder use a rectangle but can someone explain why?

Question

If you want to create a cone or cylinder by spinning a 2-dimensional shape about an axis symmetry, what shapes would you need to use, and why?

I have for a cone use a triangle and for a cylinder use a rectangle but can someone explain why?

nnesha · Answer

http://mathforum.org/brap/wrap2/highlesson.html

jim_thompson5910 · Answer

The best analogy I can think of in terms of a cylinder being formed from a rectangle is to imagine a revolving door http://revolvingdoors.net/Revolving_Door.gif the door panels are rectangles. The rectangles sweep out a 3D volume that is a cylinder

jim_thompson5910 · Answer

The axis of symmetry in this case is the pole in the center

sshayer · Answer

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