Problema Solution

A light bulb illuminates a sphere 5 meters in diameterat a distance of 7 meters. Find the area of the surface illuminated.

Answer provided by our tutors

We assume the altitude of the zone illuminated is H.

We have the formula according to the graph

H = R - R^2/D = 2.5 - 2.5^2/7 = 1.61 meters

So the area illuminated = 2*pi*R*H = 2*pi*2.5*1.61 = 8.04*pi square meters