The answer is a polyhedron
An icosahedron is a regular polyhedron with 20 equilateral triangle faces.
The figure described is a polyhedron. It is a tetrahedron known as a triangular pyramid.
In geometry, a deltahedron (plural deltahedra) is a polyhedron whose faces are all equilateral triangles. The name is taken from the Greek upper case delta (Δ), which has the shape of an equilateral triangle.
Since you use the term "faces" of a shape, you may be referring to polyhedra,which are three dimensional solids. There is no maximum number of faces a polyhedron can have. But for regular polyhedra (a special case where all faces are congruent regular polygons), the regular polyhedron with the most faces is the icosahedron, which has 20 faces, each of them an equilateral triangle. The most familiar regular polyhedron is the cube which has six square faces.
In geometry, an icosahedron is a regular polyhedron with 20 identical equilateral triangular faces.
An icosahedron is a regular polyhedron with 20 equilateral triangle faces.
The figure described is a polyhedron. It is a tetrahedron known as a triangular pyramid.
In geometry, a deltahedron (plural deltahedra) is a polyhedron whose faces are all equilateral triangles. The name is taken from the Greek upper case delta (Δ), which has the shape of an equilateral triangle.
Since you use the term "faces" of a shape, you may be referring to polyhedra,which are three dimensional solids. There is no maximum number of faces a polyhedron can have. But for regular polyhedra (a special case where all faces are congruent regular polygons), the regular polyhedron with the most faces is the icosahedron, which has 20 faces, each of them an equilateral triangle. The most familiar regular polyhedron is the cube which has six square faces.
In geometry, an icosahedron is a regular polyhedron with 20 identical equilateral triangular faces.
A tetrahedron is a three-dimensional geometric shape with four triangular faces, six edges, and four vertices. Its shape resembles a pyramid, where each of the four faces is an equilateral triangle.
Regular Tetrahedron
By its very nature of being a triangle, and a 2D shape, a triangle cannot have four plane faces. However, a tetrahedron is a polyhedron made up of four triangular faces.
There is no such thing as a 3d triangle. A 3d shape which has only equilateral triangular faces can be a tetrahedron which has 4 faces or an icosahedron which has 20.
A polyhedron with 9 faces: a nonahedron.A polyhedron with 9 faces: a nonahedron.A polyhedron with 9 faces: a nonahedron.A polyhedron with 9 faces: a nonahedron.
A polyhedron is a 3-dimensional shape whose faces are all polygons.
If they are plane faces the shape is likely to be a polyhedron.