Answer
$3\sqrt{5}$
Work Step by Step
$(x_{1}, y_{1}) = (7, 2)$ and $(x_{2}, y_{2}) = (1, -1)$
$$\sqrt{(y_{2} -y_{1})^2 + (x_{2} -y_{1})^2}$$ $$\sqrt{(-1 -2)^2 + (1-7)^2}$$ $$\sqrt{(-3)^2 +
(-6)^2}$$ $$\sqrt{9+36}$$ $$\sqrt{45} = \sqrt{9 \times 5} = 3\sqrt{5}$$
