Did You Know?
The simplest tetrahedron is made of four equal-sided triangles: one is used as the base, and the other three are fitted to it and each other to make a pyramid. But the great pyramids of Egypt aren't tetrahedrons: they instead have a square base and four triangular faces, and thus are five-sided rather than four-sided.
Origin and Etymology of tetrahedron
New Latin, from Late Greek tetraedron, neuter of tetraedros having four faces, from Greek tetra- + hedra seat, face — more at sit
First Known Use: 1570
Learn More about tetrahedron
Britannica.com: Encyclopedia article about tetrahedron
Seen and Heard
What made you want to look up tetrahedron? Please tell us where you read or heard it (including the quote, if possible).