Answer:
18
Step-by-step explanation:
[tex]\bold{METHOD\ 1:}\\\\\text{We can see in the figure that the points lie on a vertical line.}\\\text{Therefore, we can calculate the distance as on a number line.}\\\\A(3,\ 10);\ B(3,\ -8)\\\\|AB|=|-8-10|=|-18|=18[/tex]
[tex]\bold{METHOD\ 2:}\\\\\text{The formula of a distance between two points}\ A(x_A\ y_A)\ \text{and}\ B(x_B;\ y_B):\\\\|AB|=\sqrt{(x_B-x_A)^2+(y_B-y_A)^2}\\\\\text{Substittue the coordinates of the given points:}\\\\|AB|=\sqrt{(-8-10)^2+(3-3)^2}=\sqrt{(-18)^2+0^2}=\sqrt{324+0}=\sqrt{324}=18[/tex]
