An octagonal prism is one possibility.
They are prisms.
were two or more faces of a solid figure
It is a prism. More specifically, "A solid figure that has two bases that are parallel, congruent polygons and with all other faces that are parallelograms." This describes the general prism. Replace "polygons" with "triangles" and you have specified a triangular prism.
Polygonal faces.
a cube
Not aware of any solid figure with 2+3=5 rectangular faces or bases.
Triangular prism.
a triangular prism!
Probably a pentagonal prism.
Triangular Prism
Prism!
bases
It is a prism.
'Enneahedron' - a solid figure with nine faces
Triangular prisim. The three faces are rectangles, while the two bases are triangles.
A solid figure with twenty faces is called an Icosahedron.
A triangular prism. :)