An aircraft flying at an altitude of 5000 m above mean sea level takes aerial photographs of a flat terrain having an average elevation of 1000m above mean sea level. The scale of photographs is 1:20000 The focal length of the camera (in cm) is

An aircraft flying at an altitude of 5000 m above mean sea level takes

1.	An aircraft flying at an altitude of 5000 m above mean sea level takes aerial photographs of a flat terrain having an average elevation of 1000m above mean sea level. The scale of photographs is 1:20000 The focal length of the camera (in cm) is
A.	15
B.	20
C.	25
D.	30
Answer» C. 25