Question: An electric-dipole antenna is located on the roof of a 209-m-high building and is oriented vertically. An observer on the ground measures the intensity of the radiation from the antenna and finds 9.37 mW/m2. This observer is 1.01 km away from the antenna. A second observer hovers in a blimp at an altitude of 577 m and measures the radiation intensity from the antenna when she is 1.35 km from the antenna.
Part A: What intensity, in milliwatts per square meter, does she measure?
Please give me an explanation for above question.