The vertical photograph in this figure was exposed with a 10 cm focal length camera at a flying height of 2000 m above datum.

Determine the photo scale at point a if the elevation of point A on the ground is 650 m above the datum. Determine the average photo scale if the average terrain is 900 mabove datum. If the length of (ab) measures 3 cm on the vertical photograph,however, on a map plotted to a scale of 1:10000, it extends 4.5 cm, then, what is the photo scale? If the true length of CD is 450 m, then, what do you expect the length of(cd) relative to (ab), longer or shorter, clarify your answer.