The line HN = slant edge of Cheops.
Thus: Apothem of Cheops = side of decagon.
Apothem of Cheops = altitude of pentagonal pyramid.
Slant edge of Cheops = slant edge of pentagonal pyramid.
Now since apothem of Cheops = MH
and half base of Cheops = HC
then do apothem and half base represent, when taken together, extreme and mean ratio, and altitude is a mean proportional between them: it having already been stated, which also is proved by the figures in the table, that MC : MH :: MH : HC and apoth: alt :: alt : half base.
Thus is the four pointed star Cheops evolved from the five pointed star Pentalpha. This is shown clearly by Fig. 68, thus:—
Fig. 68.