That would be true because a solid object can cast a shadow
A "screen" or even just a set of parallel bars are highly reflective to electromagnetic waves as long as the open spaces are small compared to the wavelengths.
"Grid" dishes work fine ... with less weight and less wind resistance ... for frequencies below about 3 GHz. (Wavelengths of at least 10 cm.)
(I even worked on a microwave system in South America where huge grid dishes were used on a 90-mile link.)
So....
imagine the x and y axis or draw it on a piece of paper, a white board or even on your wall if you like. I'm kidding just draw it on a piece of paper
50m up and 20m down
the dog's displacement is 50 - 20 which is 30
your answer is 30m north
