# Regular Icosahedron

A regular icosahedron is a regular polyhedron composed of 20 equally sized equilateral triangles.

### Unfold of a Regular Icosahedron

### Characteristics of an Icosahedron

**Number of faces: 20**.

**Number of vertices: 12.**

**Number of edges: 30**.

**Number of concurrent edges at a vertex: 5**.

### Surface Area of a Regular Icosahedron

### Volume of a Regular Icosahedron

#### Example

Calculate the surface area and volume of a regular icosahedron with an edge of 5 cm.