Pyramid.
a square
Rhombus Hexagon Octagon Nonagon Decagon all have 7 letters
heptagon
Shapes that have more than six faces include polyhedrons such as the cube, which has six square faces, and the octahedron, which has eight triangular faces. Additionally, shapes like the dodecahedron have twelve pentagonal faces, and the icosahedron has twenty triangular faces. These shapes are examples of polyhedrons with more than six faces.
Pyramid.
A Pyramid is a 7 lettered 3D shape with triangular faces.
A triangular prism has 5 faces. Pentagonal prisms and hexagonal pyramids have 7.
Pryimaid
A pentagonal prism has 7 sides : 5 side faces and 2 bases.However, if all sides of the prism are considered faces, a shape with5 total faces including the 2 bases is a triangular prism.
A heptahedron has 7 faces, including 6 triangular faces and one hexagonal.
There are a number of possible 7-sided polyhedra. Three that come immediately to mind are: a hexagonal pyramid, a pentagonal prism, a "stretched" triangular pyramid (triangular base, rectangular sides, and then triangular faces meeting at an apex).
An octahedron is a closed 3-d shape with 8 polygonal faces. There are 257 topologically different convex octahedra. The number of triangles will depend on which one of the 257 shapes you have in mind:All 8 faces of a quadrilateral based bipyramid will be triangles.A heptagon based pyramid has 7 triangular faces.A hexagonal prism has none.
A heptagon.
Heptagon
A heptagon.
A hexagonal pyramid.================A pyramid with 7 faces has a base plus 6 triangular sides, so is called a hexagonal pyramid.