They are called a Vertices and it is where 2 edges meet.
The question is ambiguous. An octagon is a 2-dimensional shape with 8 edges and 8 vertices. Does a 3-D octagonal shape mean one with 8 edges or 8 faces or vertices, or faces which are 2d octagons?
The 3D shape that has 6 vertices, 6 faces, and 10 edges is a hexagonal prism. A hexagonal prism is a polyhedron with two hexagonal faces and six rectangular faces connecting them. It has 6 vertices where the edges meet, 6 faces (2 hexagonal and 4 rectangular), and 10 edges that form the boundaries between the faces.
There can be no such shape.
cylinder
They are called a Vertices and it is where 2 edges meet.
# of faces + # of edges + # of vertecies + 2
According to Euler none; for all 3d shapes: Vertices + Faces = Edges + 2 ⇒ 12 + 8 = 19 + 2 ⇒ 20 = 21 So unless 20 does equal 21, no 3d shape has 8 faces, 19 edges and 12 vertices. Any 3d shape with 8 faces would be an octahedron.
sphere
i would say a cube
The question is ambiguous. An octagon is a 2-dimensional shape with 8 edges and 8 vertices. Does a 3-D octagonal shape mean one with 8 edges or 8 faces or vertices, or faces which are 2d octagons?
Their relationship is modelled by the equation F + V = E + 2, where F is the number of faces, V is the number of vertices, and E is the number of edges.
The 3D shape that has 6 vertices, 6 faces, and 10 edges is a hexagonal prism. A hexagonal prism is a polyhedron with two hexagonal faces and six rectangular faces connecting them. It has 6 vertices where the edges meet, 6 faces (2 hexagonal and 4 rectangular), and 10 edges that form the boundaries between the faces.
Faces= 2 edges=5 vertices=12 Faces= 2 edges=5 vertices=12
There can be no simply connected polyhedron with the specified number of faces, vertices and edges. The Euler characteristic requires that F + V = E + 2 where F = number of faces V = number of vertices E = number of edges This requirement is clearly not satisfied.
triangular prism
That's an impossible shape. No shape can have only 2 edges.