Base of a Geometric Solid

Base of a Geometric Solid

Specific face of a solid identified for the purpose of providing a measure or a definition.

Certain solids do not have a base in the strict sense of the word. This is the case with spheres, most Platonic solids, bipyramids, etc.


  • In this illustration, the polygon on which each triangular lateral face rests is called the base of the pyramid. In this case, it is a pentagon. Therefore, the pyramid is called a pentagonal pyramid.

  • In this illustration, the base of the cylinder is a circle of radius r.

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