Definition:Deltahedron/Mistake

Source Work

 * The Dictionary
 * $8$
 * $8$

Mistake

 * A deltahedron is a polyhedron each of whose faces are triangular.

It is important to specify that the triangles in question are in fact equilateral.

This distinction is because a subsequent statement:
 * ... only $8$ of them are convex.

would be incorrect, as it would be possible to construct as many convex deltahedra as you like by constructing two pyramids whose bases are polygons with an arbitrary number of sides and placing them base to base to make a bipyramid.