A dihedral angle.
A closed three-dimensional figure formed by four or more polygons that intersect only at their edges is called a polyhedron. It contains flat faces, straight edges, and sharp corners or vertices.
There is no 3 dimensional figure with JUST 3 edges.
A tetrahedron.
a cube
A pentagonal pyramid.
Triangular pyramid
sphere
A circle.
A rhombus is a two dimensional figure while the concept of {faces, vertices and edges} is relevant to 3-dimensional shapes.
An octagon has only one face as it is a 2 dimensional figure. It has eight edges.
vertex
A rectangular prism and a cube! :)