Question

Por favor me ajudem na número 3!!!

Answer 1

 Consideremos o lado AD = x e DC = y,

 Temos que,

$\frac{12}{x}=\frac{18}{y}\\\\\frac{x}{y}=\frac{12^{\div6}}{18^{\div6}}\\\\\frac{x}{y}=\frac{2}{3}\\\\\frac{x}{y}=\frac{2k}{3k}$

 
 De acordo com o enunciado x + y = 15, então:

$x+y=15\\2k+3k=15\\5k=15\\\boxed{k=3}$


 Por fim,

$\begin{cases}\overline{AD}=x=2k\Rightarrow\overline{AD}=2\cdot3\Rightarrow\boxed{\boxed{\overline{AD}=6}}\\\overline{DC}=y=3k\Rightarrow\overline{DC}=3\cdot3\Rightarrow\boxed{\boxed{\overline{DC}=9}}\end{cases}$