Midradius
The Radius of the Midsphere of a Polyhedron, also called the Interradius. For a RegularPolyhedron with Schläfli Symbol 
, the Dual Polyhedron is 
. Denotethe Inradius 
, midradius 
, and Circumradius 
, and let the side length be 
. Then
 |  |  | (1) |
 | |  | (2) |
For Regular Polyhedra and Uniform Polyhedra, the DualPolyhedron has Circumradius
and Inradius 
. Let 
be the Angle subtended bythe Edge of an Archimedean Solid. Then | |  | (3) |
 | |  | (4) |
 | |  | (5) |
so
 | (6) |
and Circumradius gives | |  | |
|  | (7) |
for an Archimedean Solid.
References
Cundy, H. and Rollett, A. Mathematical Models, 3rd ed. Stradbroke, England: Tarquin Pub., pp. 126-127, 1989.
- Infinite Series
- Infinite Set
- Infinitesimal
- Infinitesimal Analysis
- Infinitesimal Matrix Change
- Infinitesimal Rotation
- Infinitive Sequence
- Infinitude of Primes
- Infinity
- Inflection Point
- Information Dimension
- Information Entropy
- Information Theory
- Initial Value Problem
- Injection
- Injective
- Injective Patch
- Inner Automorphism Group
- Inner Product
- Inner Product Space
- Inradius
- Inscribed
- Inscribed Angle
- Inside-Outside Theorem
- Insphere