MATHEMATICS AND ORIGAMI

Jesús de la Peña Hernández

This means that the pyramid ́s lateral side HB has equal length than the pentagon ́s di-

agonal B ́C ́ (see Fig. 1), which reminds what happened to the pyramids of polyhedron nº 3.

Fig. 3 is the folding diagram to get 4 pyramids according to Fig. 2. We need 5 blocks

like that of Fig. 3 to construct polyhedron nº 4. It happens, though, that the configurations of

Figs. 1 and 3 are not fully compatible despite of the obvious fact that 4 × 5 = 20. At the end of

the building process we require to split out the last Fig. 3 in use to get a pair of leant against to

each other pyramids and, in addition, two more isolated ones.

3

H

B

C

A

A

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