Question

Qual deve ser o valor de x na figura abaixo?

* 17
*15
*16

Answer 1

$\large\boxed{\begin{array}{l}\underline{\rm Teorema\,da\,bissetriz\,interna}\\\sf\dfrac{\overline{AB}}{\overline{AC}}=\dfrac{\overline{BD}}{\overline{DC}}\\\\\sf\dfrac{21}{\diagdown\!\!\!\!\!\!18_3}=\dfrac{x}{\diagdown\!\!\!\!\!\!12_2}\\\\\sf \dfrac{21}{3}=\dfrac{x}{2}\\\\\sf 7=\dfrac{x}{2}\\\\\sf x=2\cdot7\\\sf x=14\end{array}}}$