???

$d = \sqrt{(x_2-x_1)^2 +(y_2-y_1) ^2}$

$d = \sqrt{(5 - (-4))^2 + (-2-6)^2}$

$d = \sqrt{9^2+(-8)^2}$

$d = \sqrt{81+64}$

$d = \sqrt{145}$

d = 12.0