АВ^2=8^2+8^2-2*8*8*cos120 ° =64+64+64=64*3
[red]АВ=8*sqrt(3)
[/red]
S_(АКLB)=[red]AB[/red]*AK
S_(АКLB)=34sqrt(3)
[red]AB[/red]*AK=34sqrt(3)
[red]8*sqrt(3)*[/red]AK=34sqrt(3) ⇒ [b]AK=17/4[/b]
S_( осн)=(1/2) *a*b*sin ∠ C=(1/2)*8*8*sin120 ° =[b]16sqrt(3)[/b]
Ответ: 17/4