Which solid, no matter at which angle you cut it, will always have a circle for a cross section?

1.Icosahedron
2.Cylinder
3.Circle
4.Sphere

Question

Which solid, no matter at which angle you cut it, will always have a circle for a cross section?
 	
1.Icosahedron
2.Cylinder
3.Circle
4.Sphere

anonymous · Answer

Help me, i don't think it is a iscosashedron?? maybe a sphere?

mathstudent55 · Answer

Do you know what an icosahedron is?

anonymous · Answer

a polyhedron?

mathstudent55 · Answer

Yes, a polyhedron with 20 faces.
If you cut it with a plane, you will intercept a face or more, so you will have line segments as the intersection. So it can't be an icosahedron.

mathstudent55 · Answer

A circle is not even a solid, so that's out.

mathstudent55 · Answer

Here is a cylinder cut by a plane.
What is the cross section at the intersection?
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mathstudent55 · Answer

|dw:1407266193918:dw|

mathstudent55 · Answer

It's a rectangle, so a cylinder can't be the answer.

anonymous · Answer

sphere is the correct answer.