¶ Corollaryes added by Flussas.
Hereby it is manifest, that the diameter of a Sphere containeth in power the sides both of a pyra∣mis and of a cube inscribed in it.
For the power of the side of the pyramis is two thirdes of the power of the diameter (by the 13. of this booke). And the power of the side of the cube is, by this Proposition, one third of the power of the sayd diameter. Wherefore the diameter of the Sphere contayneth in power the sides of the pyra∣mis and of the cube..
All the diameters of a cube cut the one the other into two equall partes in the centre of the sphere which containeth the cube. And moreouer those diameters do in the selfe same point cut into two e∣quall partes the right lines which ioyne together the centres of the opposite bases.
As it is manifest to see by the right line LOF. For the angles LKO, and FIO, are equall, by the 29. of the first: and it is proued, that they are contained vnder equall sides: Wherefore (by the 4. of the first) the bases LO and FO are equall. In like sort may be proued, that the rest of the right lines which ioyne together the centres of the opposite bases do cut the one the other into two equall partes in the centre O.