Online Math Dictionary: I

Easy to understand math definitions for K-Algebra mathematics
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icosahedron icosidodecahedron identity
additive identity
identity
multiplicative identity
imaginary number improper fraction
inequality infinite infinity
inscribed integer intersection
intersection of sets inverse
additive inverse
inverse
multiplicative inverse
irrational number isosceles triangle isosceles trapezoid

 

Icosahedron
An icosahedron is a polyhedron made up of twentyequilateral triangles.  It is one of the five Platonic Solids.
     
20 faces: equilateral triangles
     12 vertices
     30 edges
     Dihedral angle: about 138.19 degrees

For more info about Platonic solids, check out myPlatonic solids gallery.

icosahedron

red line

Icosidodecahedron
An icosidodecahedron is a polyhedron - one of the thirteen semi-regular Platonic solids.  It's
 created by either cutting (truncating) the dodecahedron one half of the way into each side or cutting (truncating) the icosahedron one half of the way into each side.
     32 total faces: 20 equilateral triangles and 
                                 12 regular pentagons
 
     30 vertices: 2 triangles and 2 pentagons
     60 edges
     
Dihedral angle: about 142.623 degrees

For more info about Platonic solids, check out myPlatonic solids gallery.

icosidodecahedron