20. The illustration shows a plane taking an aerial photograph of point A. Because the point is directly below the plane, there is no distortion in the image. For any point B
not directly below the plane, however, the increase in distance creates distortion in
the photograph. This is because as the distance from the camera to the point being
photographed increases, the exposure of the film reduces by (sin )(csc 0 - sin o).
Express (sin )(csc o - sin e) in terms of cos O only.