It looks like you have to do distance formula. It's basically this:
D = [tex]\sqrt{(y_{2}-y{1})^{2} + (x_{2}-x{1})^{2} }[/tex] (ignore the A, i dont know how to get rid of it sorry)
I would then plug in the points of A(1,7) and B(10,3).
D = [tex]\sqrt{(7-3)^2 + (10-1)^2 }[/tex]
Then I would get the square root of 4^2 + 9^2
= square root of 16 + 81
= square root of 97
So the length of AB would be the square root of 97
