Find the diameter of the moon's diameter on the slide film.?

Question

Given that the diameter of the moon is 3.48*10^6m and the distance from the earth is 4*10^8m. The moon is being photographed by a camera whose lens has a focal length of 0.005m.

Answer 1

d = 3.48E6*.005/4E8 = .0000435 m = .0435 mm