Final answer:
An icosahedron is a symmetrical, solid shape with 20 triangular faces and 12 corners.
Step-by-step explanation:
An icosahedron is a symmetrical, solid shape that has 20 faces. Each of these faces is an equilateral triangle. The structure of an icosahedron also includes 12 corners, where the faces meet. This geometric shape is an example of a regular polyhedron, one of the five Platonic solids, which are convex polyhedra with faces made of congruent regular polygons.