On a vertical photograph, images a and b of ground points A and B have photographic coordinates xa = 3.27 in., ya = 2.28 in., xb = -1.95 in. and yb = -2.50 in. The horizontal distance between A and B is 5283 ft, and the elevations of A and B above datum are 646 ft and 756 ft, respectively. Using Equation (27.9), calculate the flying height above datum for a camera having a focal length of 152.4 mm.