The brightness I of a light beam that illuminates some surface is expressed by the formula (will put in comments) . Where k is a constant for the given source, r is the distance between the source and the illuminated point and Theta is the angle between the light ray and the surface. At what height should you suspend the lamp over the round table of radius "a" so that the edge of the table becomes maximally bright?

Question

carissa15 · Answer

$$I=\frac{ k \sin \phi }{ r^2 }$$