Tetrahedron facts for kids

A rotating tetrahedron

A tetrahedron (triangular pyramid) is a three-dimensional shape. It has four corners. It looks like a pyramid. It has six equally long edges, four corners and four equilateral triangular faces. Every two edges meet on one of those corners forming a sixty-degree angle. All of its sides are triangles.

Formulas for a regular tetrahedron

A regular tetrahedron is a tetrahedron where all of its edges are the same length. If the length of an edge is a:

Surface area	${\sqrt{3}}a^2\,$
Face area	$\frac{\sqrt{3}}{4}a^2\,$
Height	$\sqrt{\frac23}\,a\,$ and $\frac{\sqrt{6}}{3}a$
Volume	$\frac{a^3}{6\sqrt{2}}\,$ and $\frac{\sqrt{2}}{12}a^3$

Images for kids

Tetrahedron (Matemateca IME-USP)
Five tetrahedra are laid flat on a plane, with the highest 3-dimensional points marked as 1, 2, 3, 4, and 5. These points are then attached to each other and a thin volume of empty space is left, where the five edge angles do not quite meet.
A central cross section of a regular tetrahedron is a square.
A tetragonal disphenoid viewed orthogonally to the two green edges.
A single 30-tetrahedron ring Boerdijk–Coxeter helix within the 600-cell, seen in stereographic projection
The stella octangula.
An irregular volume in space can be approximated by an irregular triangulated surface, and irregular tetrahedral volume elements.
Six edge-lengths of Tetrahedron
The ammonium ion is tetrahedral
4-sided dice
Compound of five tetrahedra
Compound of ten tetrahedra

Tetrahedron facts for kids

Formulas for a regular tetrahedron

Images for kids

See also