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**## Tetrahedron: All four faces are equilateral triangles

The radius of a circumscribed sphere of tetrahedron is

,where "*a"* is side length

The radius of an inscribed sphere of tetrahedron is

The surface area of tetrahedron

It is possible to represent the surface area of tetrahedron as an area of the model for better illustration.

The volume of tetrahedron is

The height of the tetrahedron is determined by the following formula:

The distance to the center of the base of the tetrahedron is determined by the formula:

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