Consider the triangles ABC and DCE, these triangles are similar, because ∠C is common, ∠B and ∠DEC are straight, and the angles A and EDC are equal, as they are corresponding.
It follows from the similarity of these triangles that AB / DE = BC / EC, AB / DE = (BE + EC) / EC, hence (AB * EC) / DE = BE + EC
BE = (AB * EC) / DE-EC
BE = (5 * 9) / 1.8-9 = 16
Answer: the distance from the lamp to the person is 16 m
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.