An air base of 3205 ft exists for a pair of overlapping vertical photographs taken at a flying height of 5500 ft above MSL with a camera having a focal length of 152.4 mm. Photo coordinates of points A and B on the left photograph are xa = 40.50 mm, ya = 42.80 mm, xb = 23.59 mm, and yb = -59.15 mm. The x photo coordinates on the right photograph are x1a -60.68 mm and x1b-70.29 mm. Using the parallax equations, calculate horizontal length AB.