Britannica Sources used in this answer

How many faces does a tetrahedron have?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

Map of the Greco-Roman world highlighting the birthplaces of notable ancient mathematicians, marked with the pi symbol and labeled with their names. Cities such as Athens, Alexandria, Syracuse, and Miletus are shown around the Mediterranean, with modern country boundaries outlined. An inset provides detail for the region of Greece and western Anatolia. — geometry This map spans a millennium of prominent Greco-Roman mathematicians, from Thales of Miletus (c. 600 bce) to Hypatia of Alexandria (c. 400 ce).

A tetrahedron has four faces. In Euclidean geometry, it is defined as a polyhedron composed of four polygonal surfaces that meet at edges and vertices.1

While the simplest version consists of four equal-sided triangles, it is distinct from other pyramid-like structures, such as those with square bases, which possess five faces. The tetrahedron is also recognized as a Platonic solid.21