Question Number 183620 by a.lgnaoui last updated on 27/Dec/22
$${determiner}\:{l}\:{aire}\:\:{du}\:{triangle}\:{CDE} \\ $$
Commented by a.lgnaoui last updated on 27/Dec/22
Answered by HeferH last updated on 27/Dec/22
$$\:{By}\:{seeing}\:{some}\:{similar}\:{triangles}, \\ $$$$\:{CDE}\:{its}\:{a}\:{special}\:{right}\:{triangle}\::\:\mathrm{3}{k},\:\mathrm{4}{k},\:\mathrm{5}{k} \\ $$$$\:\mathrm{15}\:\left({CDE}\:{hipotenuse}\right)\:=\:\mathrm{5}{k} \\ $$$$\:{k}\:=\:\mathrm{3} \\ $$$${A}\:=\:\frac{\mathrm{9}\centerdot\mathrm{12}}{\mathrm{2}}\:=\:\mathrm{54}\:{u}^{\mathrm{2}} \\ $$
Commented by a.lgnaoui last updated on 27/Dec/22
$${OK},{thanks} \\ $$