Assuming that a solid triangle is a tetrahedron, the answer is: faces: 4 edges: 6 vertices: 4
a triangle
Tetrahedron
a pyramid
There are 2 triangle base faces, and 3 rectangle faces. 5 total faces.
triangle based pyramids
pyramid
Tetrahedron: It is the smallest "regular solid" (Edges=Faces+Corners-2), 4 faces, each one an equilateral triangle. 4 corners
Isosceles TetrahedronA solid with four faces is a tetrahedron. Each of the faces is a triangle. If all the triangles are congruent, you have an isosceles tetrahedron.
A cube and an equilateral triangle based pyramid
Octogon
A 3D shape with one base and three faces can only have triangular faces.