CK12 - Geometry

So now a questionarises.Giventhat a polyhedronis regularif all of its facesare congruentregularpolygons,
it is convexand containsno gapsor holes.How manyregularpolyhedraactuallyexist?

In fact, you may be surprisedto learnthat only five regularpolyhedracan be made.Theyare knownas the
Platonic(or noble)solids.

Notethat no matterhow you try, you can’tconstructany otherregularpolyhedrabesidesthe onesabove.

Example 8

How manyfaces,edges,and verticesdoesa tetrahedron(see above)have?

Faces:4, edges:6, vertices: 4

Example 9

Whichregularpolygondoesan icosahedronfeature?

An equilateraltriangle

ReviewExercises

Identifyeachof the followingthree-dimensionalfigures:

1.