Задача 40389.

Above the small stage at the height of 5 meters, two lamps are placed, giving full light output, respectively 9420 and 12560 lumens. The distance between them is 8.6 m, which is equal to the illumination of the scene under the lights in the middle of the distance between them?

Detailed solution with a short recording conditions, laws and formulas used in the decision, the withdrawal of the calculation formula and the answer.
If you have any questions about the decision to write. I try to help.