Question

Giups em với

Answer 1

\(S_{JKML}=JK.KM\)

\(S_{\Delta JKN}=\dfrac{1}{2}JK.KN=\dfrac{1}{2}JK.\dfrac{2}{3}KM=\dfrac{1}{3}JK.KM=\dfrac{1}{3}S_{JKML}\)

\(S_{\Delta JLO}=\dfrac{1}{2}JL.LO=\dfrac{1}{2}JL.\dfrac{1}{2}LM=\dfrac{1}{4}JL.LM=\dfrac{1}{4}KM.JK=\dfrac{1}{4}S_{JKML}\)

\(S_{OMN}=\dfrac{1}{2}OM.NM=\dfrac{1}{2}.\dfrac{1}{2}LM.\dfrac{1}{3}KM=\dfrac{1}{12}LM.KM=\dfrac{1}{12}S_{JKML}\)

Mà \(S_{JKML}=S_{\Delta JKN}+S_{\Delta OMN}+S_{\Delta JLO}+S_{\Delta NJO}\)

\(\Rightarrow S_{JKML}=\dfrac{1}{3}S_{JKML}+\dfrac{1}{4}S_{JKML}+\dfrac{1}{12}S_{JKML}+18\)

\(\Leftrightarrow\dfrac{1}{3}S_{JKML}=18\)

\(\Leftrightarrow S_{JKML}=54\left(cm^2\right)\)