Answer: 6 feet is the greatest distance that a person could be from the lamp and be detected.
Explanation:
Since we have given that
The equation is :

It is the equation of circle in which center is (h,k) i.e. (-16,13)
The general equation of circle is given by

Here, the radius 'r' is given by

Here, the greatest distance a person could be from the lamp and be detected is represented by radius i.e. r = 6 feet.
Hence, 6 feet is the greatest distance that a person could be from the lamp and be detected.