It depends on a decagonal what.
A decagonal prism has 20 vertices.
A decagonal pyramid has 11 vertices.
A decagonal based pyramid will have 11 faces, 11 vertices and 20 edges
The question cannot be answered because it makes no sense. "Decagonal" is an adjective, not a noun and the answer will depend on whether the question is about a decagonal pyramid, a decagonal prism or decagonal bipyramid, or something else.
11 vertices (one more than the number of vertices in the base).
12 faces 20 vertices 30 edges
Not sure what a decagonal is. Since the question refers to faces, edges and vertices, it may be assumed that the object in question is 3-dimensional. A decagon certainly is not, so decagonal cannot be a mistaken name for a decagon.
A decagonal prism has 20 vertices: 10 at each end.
A decagonal prism has 20 vertices: 10 at each end.
20 vertices.
A decagonal based pyramid will have 11 faces, 11 vertices and 20 edges
The question cannot be answered because it makes no sense. "Decagonal" is an adjective, not a noun and the answer will depend on whether the question is about a decagonal pyramid, a decagonal prism or decagonal bipyramid, or something else.
11 vertices (one more than the number of vertices in the base).
Vertices: 20 Edges: 30 Faces: 12
By "corners", do you mean vertices or edges?
Edges = 30 Faces = 12 Vertices = 20
12 faces 20 vertices 30 edges
20 edges, 11 vertices (corners) and 11 faces.
11 faces and 11 corners (vertices).