Step-by-step explanation:
[tex]\text{The length between 2 points, } (x_1, y_1)\text{ and }(x_2,y_2)\text{ is determined by, }[/tex]
[tex]d=\sqrt{(x_2-x_1)^2+(y_2-y_1)^2}[/tex]
[tex]\text{The length between } (12, -22)\text{ and }(8, -30)\text{ is determined by, }[/tex]
[tex]d=\sqrt{(8-12)^2+(-30-(-22))^2}=\sqrt{4^2+8^2}=\sqrt{4^2(1+2^2)}=4\sqrt5[/tex]