Poy
There is no pentahedron with only one triangular face.
No. I has 3 triangle faces and one square face.
All but one face must be triangular. The base can be any polygon, including a triangle.
triangular prism
Two three-dimensional shapes that have at least one triangle as a face include a triangular prism and a pyramid. In a pyramid, the outer faces are triangles, and they come together at one point. A triangular prism is a type of prism with a triangular base.
4 faces. The number of faces on a pyramid is one more than the number of sides of the base. A triangle has 3 sides, therefore a triangular pyramid has 3 +1 = 4 faces.
The shape described is a triangular prism.
A triangular pyramid - one with four faces, each face being a triangle.
The solid shape that has one square face and four triangular faces is called a pyramid. If you were to have a shape that had four triangular faces and no square face, it would be called a triangular pyramid.
An octagon is a plane shape with just one face - an octagonal face! It cannot have triangular faces.
It is a hexahedron. There are several types of hexahedron, one of which is the cube. One having 6 triangular faces is a triangular dipyramid.
There are several triangular polyhedra. The simplest is a tetrahedron with 4 faces, but you can have a triangular dipyramid (two tetrahedra stuck together along one face) which has 6 faces. Then there is the icosahedron with 20 faces. The tetrahedron and icosahedron are Platonic solids, but there are many more.