A lamp produced a shadow of a man standing in the middle of the sta produced a shadow of a man standing in the middle of a stage. how long is the shadow

First, illustrate the problem.

Draw a lamp and a man standing in the middle of a stage, then draw a shadow of a man. Assign the lamp as one of the legs of the triangle and the other leg is the distance of the man from the lamp and the hypotenuse is the shadow of the man. Use the Pythagorean theorem and similar triangles.