Utilizando a lei dos senos, temos:
[tex]\dfrac{AC}{sen60\°}=\dfrac{AB}{sen45\°}\\\\\dfrac{x}{\frac{\sqrt{3}}{2}}=\dfrac{8}{\frac{\sqrt{2}}{2}}\\\\x=8\cdot\dfrac{2}{\sqrt{2}} \cdot\dfrac{\sqrt{3}}{2}\\\\x=\dfrac{8\sqrt{3}}{\sqrt{2}}\quad\mbox{racionalizado obtemos}\\\\\boxed{\boxed{x=4\sqrt{6}}}[/tex]
