Answer:
The volume of a tetrahedron can be found using the formula:
V = (1/3) * A * h
where A is the area of one of the faces of the tetrahedron, h is the height of the tetrahedron, and V is the volume of the tetrahedron.
In this case, we are given that the area of one of the faces is 21 m² and the height of the tetrahedron is 6 m. Substituting these values into the formula, we get:
V = (1/3) * 21 m² * 6 m
V = 42 m³
Therefore, the volume of the tetrahedron is 42 cubic meters.