$\left|d\right|=\sqrt{\left(x_2-x_1\right)^2+\left(y_2-y_1\right)^2}$
$\sqrt{6^2+\left(-2\right)^2}=\sqrt{40}=2\sqrt{10}$
$\begin{array}{l}\sqrt{-1^2+7^2} \\ \end{array}=\sqrt{50}=5\sqrt2$
$\sqrt{5^2+5^2}=5\sqrt2$
$\begin{align*} & \\ & \end{align*}$