Answer:
9
Step-by-step explanation (the suggested solution is not the shortest way):
1. formula is
[tex]length=\sqrt{(x_b-x_a)^2+(y_b-y_a)^2};[/tex]
2. using the formula described above:
[tex]length=\sqrt{(6+3)^2+(7-7)^2} =9[/tex]
