Polyhedron
3-D solid formed only by polygons
faces- polygonal sides of a solid
edges- segmental boundaries of each face
vertices- points where edges meet

*What solids aren’t polyhedrons?
usually formed with circles and/or smooth faces
Examples: cones, spheres, and cylinders

The Types of Polyhedrons

*Prisms

    -contain 2 bases (named for the bases)

    -side faces are rectangles

*Pyramids

    -contain one base (named for the base)

    -side faces are triangles that meet at a vertex opposite of base

*Platonic Solids

    -all faces are made of regular polygons

    -named for the number of faces

    -There exist only five made of only triangles, squares, and pentagons

    -known as regular polyhedrons

(The five platonic solids)

*Tetrahedron

    -4 equilateral triangles

    -tetra- 4-sided

    -hedron- 3-D solid

    -aka triangular pyramid

*Hexahedron

    -6 squares

    -hexa- 6- sided

    -hedron- 3-D solid

    -aka cube or square prism

*Octahedron

    -8 equilateral triangles

    -octa- 8-sided

    -hedron- 3-D solid

    -same as 2 square pyramids placed together

*Dodecahedron

    -12 regular pentagons

    -dodeca- 12-sided

    -hedron- 3-D solid

*Icosahedron

    -20 equilateral triangles

    -icosa- 20-sided

    -hedron- 3-D solid