A regular tetrahedron has four congruent equilateral-triangle faces. Each face has area rac{sqrt{3}}{4}a^2.

Multiply that by four to get the total surface area: $sqrt{3}a^2$.

Surface area appears in coating, wrapping, and material estimation problems involving triangular pyramids and Platonic-solid examples.

The preview helps separate visible faces from hidden edges, which is useful when translating the formula back to the solid.