Because that is how a polyhedron is defined.
Because that is how a polyhedron is defined.
Because that is how a polyhedron is defined.
A polyhedron.
It is so by definition.
Sphere
cube
312
A triangle is not a polyhedron. A triangle is a two-dimensional figure, and a polyhedron is a three-dimensional solid. An example of a triangular-shaped polyhedron is a pyramid.
Cube, parallelogram, and prism
It is a sphere which looks like a globe
No. A polygon is a 2-dimensional figure. A polyhedron is 3-dimensional.
A polyhedron is a closed figure with several (planar) sides, and all its sides are planar. A non polyhedron does not have these properties, maybe it is not closed, maybe one or more of the sides is a curved surface. In some branches of topology the sides of a polyhedron cannot intersect each other.