Resposta :
[tex]\Large\boxed{\begin{array}{l}\underline{\rm Observe~a~figura~que~eu~anexei.}\\\sf d^2=8^2+12^2\\\sf d^2=64+144\\\sf d^2=208\\\sf d=\sqrt{208}\\\sf d=\sqrt{16\cdot13}\\\sf d=4\sqrt{13}\,cm\end{array}}[/tex]

[tex]\Large\boxed{\begin{array}{l}\underline{\rm Observe~a~figura~que~eu~anexei.}\\\sf d^2=8^2+12^2\\\sf d^2=64+144\\\sf d^2=208\\\sf d=\sqrt{208}\\\sf d=\sqrt{16\cdot13}\\\sf d=4\sqrt{13}\,cm\end{array}}[/tex]