S(осн.)=a^2sqrt(3)/4=6^2*sqrt(3)/4=9sqrt(3)
S(бок.)=3*S( Δ SBC)
OM=r=a/(2sqrt(3))=6/(2sqrt(3))= sqrt(3)
∠ SMO=60 градусов.
SM=OM/cos60^(o)=sqrt(3)/(1/2)=2sqrt(3)
S( Δ SBC)=(1/2)BC*SM=(1/2)*6*2sqrt(3)=6sqrt(3)
S(бок.)=3*S( Δ SBC)=3*6sqrt(3)=18sqrt(3)
S(полн.)=S(бок.)+S( осн.)=18sqrt(3)+9sqrt(3)=27sqrt(3)