CHAPTER 3. GEOMETRY

311. 
     

     p=O~O P=

     
     


312. 
     

     P

     
     

~ O

s

P

= =

=

=

Icosahedron

=

=

=

Figure 45.

=

( )

NO

~ PP R

ê

+

= =

=

314. O()R R

Q

~

o= + =

=

315. 
     

     p=R~O P=

     
     


316. 
     

( )

NO

R~ P R

s

P +

= =

=

=