If the prism is based on regular decagons and it is a right prism, all 12 faces.
A decagonal based pyramid will have 11 faces, 11 vertices and 20 edges
12 faces 20 vertices 30 edges
It has 9 faces It has 21 edges Its end faces are parallel to each other
its has parallel faces and edges
12 faces * * * * * Correct as far as it goes, but incomplete. 20 vertices 30 edges
A decagonal based pyramid will have 11 faces, 11 vertices and 20 edges
12 faces 20 vertices 30 edges
Edges = 30 Faces = 12 Vertices = 20
It has 9 faces It has 21 edges Its end faces are parallel to each other
20
20 edges, 11 vertices (corners) and 11 faces.
Vertices: 20 Edges: 30 Faces: 12
its has parallel faces and edges
Assuming a regular decagon is the base of the prism, it would be 10 faces. With an irregular decagon, it is possible that two (or more) of the edges of the decagons are perpendicular, so all 12 faces could have perpendicular edges.
A triangular-based pyramid, also called a tetrahedron, has no parallel faces, but has 4 faces, 6 edges and 4 vertices
19 * * * * * Actually it is 30 edges. Ten around each of the decagonal faces, and ten more connecting the corresponding vertices of the two decagons.
12 faces * * * * * Correct as far as it goes, but incomplete. 20 vertices 30 edges