# Pentahedron

Pronunciation: /ˌpɛn.təˈhi.drən/ Explain

 Click on the blue points and drag them to change the figure. Click on a blank area of the screen and drag to rotate the figure. Manipulative 1 - Pyramidal Pentahedron Created with GeoGebra.

 Click on the blue points and drag them to change the figure. Can you think of any other pentahedron? Manipulative 2 - Triangular Prism Created with GeoGebra.

A pentahedron is a five sided polyhedron. There is no regular pentahedron. There are two pentahedrons that can exist in Euclidean 3-space. One is a square pyramid (see manipulative 1).

### Geometric Nets

A geometric net is a shape that can exist in 2-space, which can be folded into a polyhedron. Click on the name of the net to download a printable net you can cut out and decorate.

Pentahedron Nets
ImageNameDescription
Triangular Prism A triangular prism has identical triangles as base and top with straight sides.
Square Pyramid A square pyramid has a square bases with straight sides that come to a point.
Table 1

### Irregular Pentahedron Net

Manipulative 3 is an irregular pentahedron net you can change, print out, and put together. Click on the blue points to change the net. If any part of the net disappears or any of the lines cross, you have created a net that can not be constructed.

 Click on the blue points and drag them to change the figure. Print the figure out and tape it together to make an irregular pentahedron. Why do three of the points around the edge of the figure have movable points and the fourth does not? Manipulative 3 - Net of an Irregular Pentahedron Created with GeoGebra.

### References

1. McAdams, David E.. All Math Words Dictionary, pentahedron. 2nd Classroom edition 20150108-4799968. pg 136. Life is a Story Problem LLC. January 8, 2015. Buy the book

• McAdams, David E.. Polyhedron. allmathwords.org. All Math Words Encyclopedia. Life is a Story Problem LLC. 3/12/2009. http://www.allmathwords.org/en/p/polyhedron.html.
• Euclid of Alexandria. Elements. Clark University. 9/6/2018. https://mathcs.clarku.edu/~djoyce/elements/elements.html.

McAdams, David E. Pentahedron. 3/26/2019. All Math Words Encyclopedia. Life is a Story Problem LLC. http://www.allmathwords.org/en/p/pentahedron.html.

### Revision History

12/21/2018: Reviewed and corrected IPA pronunication. (McAdams, David E.)
9/25/2008: Initial version. (McAdams, David E.)

All Math Words Encyclopedia is a service of Life is a Story Problem LLC.