A polyhedron is a hard with level faces(from Greek poly- meaning "many" and -hedron an interpretation "face").

You are watching: All polyhedrons are prisms or pyramids

CubeIts deals with are all squares
Triangular PrismIts encounters are trianglesand rectangles
DodecahedronWhat deals with does it have?

So no curved surfaces: cones, spheres and cylinders room not polyhedrons.

## Common Polyhedra    Platonic Solids  Prisms   Pyramids

Note: the plural of polyhedron is one of two people polyhedrons or polyhedra

## Many More Explore 100s of animated Polyhedron Models.You can likewise see some photos of Polyhedra if girlfriend want.

## Counting Faces, Vertices and also Edges

When us count the variety of faces (the level surfaces), vertices (corner points), and edges that a polyhedron we uncover an amazing thing:

The number of facesplus the variety of verticesminus the variety of edges equates to 2

This can be written nicely as a small equation:

### F + V − E = 2

It is known as Euler"s Formula (or the "Polyhedral Formula") and also is really useful come make sure we have actually counted correctly!

### Example: Cube

A cube has:

6 Faces8 Vertices (corner points)12 Edges

F + V − E = 6 + 8 − 12 = 2

### Example: triangular Prism

This prism has:

5 Faces6 Vertices (corner points)9 Edges

F + V − E = 5 + 6 − 9 = 2

But over there are cases where it does not work! check out Euler"s Formula because that more.

See more: How Many Ml In 1 Unit Of Blood ? How Many Milliliters Are In One Unit ## Diagonals

A diagonal is a straight line within a form that goes native one edge to one more (but not an edge).

A polyhedron deserve to have several diagonals. Have the right to you think that one there is no diagonals?

Geometry solid Geometry Platonic Solids prisms