Question

Cho tg abc vg tại a,đg cao ai.Có bc=18,bi=6,ic=12.Tính Sabc,Saib

Answer 1

Có : \(AI^2=BI.IC\Leftrightarrow AI^2=6.12=72\Rightarrow AI=6\sqrt{2}\)

\(S_{ABC}=\dfrac{1}{2}AI.BC=\dfrac{1}{2}.6\sqrt{2}.18=54\sqrt{2}\)

\(S_{AIB}=\dfrac{1}{2}BI.AI=\dfrac{1}{2}6\sqrt{2}.6=18\sqrt{2}\)

Answer 2

có : AI²= BI . IC <=> AI² = 6 . 12 = 72 => AI = 6√2

S_ABC = 1/2 AI . BC = 1/2 . 6√2 .18 = 54√2

S_ABC = 1/2 BI . AI = 1/2 6√2 . 6 = 18√2