Question

Can a polyhedron have for its faces
(i) $3$ triangles?
(ii) $4$ triangles?
(iii) a square and four triangles?

Answer 1

A polyhedron has to have a minimum of four faces. Hence (i) is not possible but (ii) and (iii) are possible.

A polyhedron with 4 triangles as faces is called a triangular pyramid and one with one square and four triangles is called a square based pyramid.