Regular or equilateral tetrahedron – all edges are equal, and the faces, respectively, are equilateral triangles.
The formula for the surface area of an equilateral tetrahedron:
where is the a-side
Rectangular tetrahedron – the angle between all three edges at one vertex is straight, i.e. equal to 90°
The formula for the surface area of a rectangular tetrahedron:
where a,b,c are the sides at an angle of 90°, d,e,f are the sides of the base