Icosahedron
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(1) A general icosahedron is any polyhedron having 20 faces. (2) The regular icosahedron is the Platonic solid comprised of 20 equilateral triangles, 12 vertices, and 30 edges.
Icosahedron is a middle school-level concept.
Prerequisites
| Platonic Solid: | The Platonic solids are the five convex solids composed of identical regular polygons. |
| Regular Polygon: | A regular polygon is a polygon in which the sides are all the same length and the angles all have the same measure. |