Answer: L=15.
Step-by-step explanation:
Line length formula
[tex]\boxed {L=\sqrt{(x_2-x_1)^2+(y_2-y_1)^2} }[/tex]
x₁=-5 x₂=7 y₁=4 y₂=-5.
Hence,
[tex]L=\sqrt{(7-(-5))^2+(-5-4)^2}\\L= \sqrt{(7+5)^2+(-9)^2}\\ L=\sqrt{12^2+9^2}\\ L=\sqrt{144+81} \\L=\sqrt{225} \\L=\sqrt{15^2} \\L=15.[/tex]