Answer:
midpoint = ((3 + 5)/2, (2 + 6)/2) = (4, 4)
slope = (6 - 2)/(5 - 3) = 4/2 = 2
The perpendicular bisector will have slope -1/2 and will go through (4, 4).
4 = (-1/2)(4) + b
4 = -2 + b
b = 6
y = (-1/2)x + 6
y = 0--->x = 12, so A is at (12, 0).
x = 0--->y = 6, so B is at (0, 6).
AB = √(12² + 6²) = √180 = √36√5 = 6√5