Question Number 84899 by Power last updated on 17/Mar/20
Commented by Tony Lin last updated on 17/Mar/20
$${A}\left({ADE}\right)=\mathrm{9} \\ $$$$\Rightarrow{h}=\mathrm{6} \\ $$$${A}\left({EFC}\right) \\ $$$$=\frac{\mathrm{1}}{\mathrm{2}}×{EC}×\left({h}×\frac{\mathrm{6}}{\mathrm{7}}\right) \\ $$$$=\frac{\mathrm{1}}{\mathrm{2}}×\mathrm{6}×\frac{\mathrm{36}}{\mathrm{7}} \\ $$$$=\frac{\mathrm{108}}{\mathrm{7}} \\ $$