V.  9.  13.
9.  constr.
6.  sch.  13.  6.

396  EVCLIDIS  ELEMENT.
2.  Quia  VX,  XY  sunt
latera  hexagoni  &  decagoni; ¬
  erit  YYV:  VXVX: =
  XY.  Hinc  ?  YV;
VK  =  KV:  VZ.  Ergo
super  YZ  descriptus  semicirculus“ ¬
  transibit  per  K.
Similiter  quia  ZX  =YV,
&  PX.=  VX,  erit  ZX:
C
XP  =  PX:  XY,  &  hinc,
ob  ang.  ad  X  rectos,  semiB ¬

circulus  super  ZY  transibit ¬
  etiam  per  P.  Quare
quum  idem  similiter  de  reliquis  verticibus
angulorum  icosaedri  ostendi  possit;  constat,
semicirculum  circa  ZY  manentem  rotatum
transiturum  esse  per  vertices  omnium  angulorum ¬


A