A 1.6m-tall pedestrian walks along a straight sidewalk away from a 4m streetlamp. The sidewalk is level, and the tip of the pedestrian’s shadow always touches the ground.
Let x be the horizontal distance (in meters) between the pedestrian and the base of the lamp, and let s be the length (in meters) of the pedestrian’s shadow.
Which of the following equations best expresses the geometric relationship among x, s, and the two given heights?
(a) 1.6x=4x+s
(b) 1.6s=4x+s
(c) 1.6s=4x
(d) 4s=1.6x+s