OO_(2)=(2/3)R
По теореме Пифагора
r^2_(2)=R^2-((2/3)R)^2;
[b]r^2_(2)=(5/9)R^2[/b]
S_(ω_(2))=5π
π*r^2_(2)=5π
(5/9)R^2=5
R^2=9
S_(cферы)=4πR^2=4π*9=36π
О т в е т. 36π
12.
OO_(1)=(1/6)R
OO_(2)=(4/6)R
По теореме Пифагора
r^2_(1)=R^2-((1/6))R^2
r^2_(1)=35R^2/36
По теореме Пифагора
r^2_(2)=R^2-((4/6))R^2
r^2_(2)=20R^2/36
S_(ω_(1))+S_(ω_(2))=55π
πr^2_(1)+πr^2_(2)=55π
Делим на π
и подставляем r^2_(1)=35R^2/36; r^2_(2)=20R^2/36 :
(35R^2/36) + (20R^2/36) = 55
R^2=36
S_(cферы)=4πR^2=4π*36=144π
О т в е т. 144π