A square plane mirror of side length s s hangs on a wall such that its bottom edge is a height h h above the floor. The wall opposite the mirror is a distance d d away. Marco, whose eyes are at the exact height of the center of the mirror, stands directly in front of the mirror at the center of its width. Derive an expression for the maximum distance x x that Marco can stand from the mirror and still see the reflection of the bottom of the wall behind him. Assume that s < 2 h .