209

\sqrt{\left(9-1\right)^2+\left(10-4\right)^2}
\sqrt{64+36}
\sqrt{100}=10\ \left(tai\ -10\right)
\sqrt{\left(1-\left(-1\right)\right)^2+\left(5-1\right)^2}
\sqrt{4+16}
\sqrt{20}
2\sqrt{5}