Mathematics

Problem

1.6\,\text{m}

-tall pedestrian walks along a straight sidewalk away from a

4\,\text{m}

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)

\displaystyle \frac{x}{1.6}=\frac{x+s}{4}

\displaystyle \frac{s}{1.6}=\frac{x+s}{4}

\displaystyle \frac{s}{1.6}=\frac{x}{4}

\displaystyle \frac{s}{4}=\frac{x+s}{1.6}