S_(1)=a
a=π*R_(1)^2 ⇒ R^2_(1)=a/π ⇒[b] R_(1)=sqrt(a/π)[/b]
S_(2)=π*R_(2)^2
S_(2)=b
b=π*R_(2)^2 ⇒ R^2_(2)=b/π ⇒[b] R_(2)=sqrt(b/π)[/b]
С_(1)=2π*R_(1)
С_(2)=2π*R_(2)
C_(1):C_(2)=R_(1):R_(2)=sqrt(a/π):sqrt(b/π)=[b]sqrt(a/b)[/b]
Ответы: а/в, а/2в,[b] √а/в[/b], (а/в)2