Your question is unclear but here is my try.
Given (0, 5) and (5, 0), find the distance between the two points.
Let (0, 5) and (5, 0) be the two points.
Let d = distance
d = sqrt{(5 - 0)^2 + (0 - 5)^2}
d = sqrt{(5)^2 + (-5)^2}
d = sqrt{25 + 25}
d = sqrt{50}
d = sqrt{25}•sqrt{2}
d = 5•sqrt{2}