If Keiji stands on top of a hill at sunset and gazes at his elongated shadow stretching down the hill, what will happen to the length of his shadow if he takes a few steps back up the hill?

Respond very briefly.
The length of Keiji's shadow will increase as he takes steps back up the hill. When Keiji moves higher up the slope, his position relative to the point where the shadow starts on the hilltop moves further from the base of the hill, thus extending the shadow. Considering the sun is low in the sky during sunset, the angle at which the sunlight is hitting him causes longer shadows. Since the sun's position doesn't change significantly during the short time he's moving, the shadow's length is primarily affected by his change in position relative to the sun. As he moves up, the angle of the shadow relative to the ground becomes sharper, thus lengthening the shadow down the hill.