Question

A rod that is 12 centimeters long is held between a flashlight and a wall as shown below. The rod is held parallel to the wall. The flashlight is 60 cm away from the wall, and the rod is 45 cm away from the wall. Find the length of the shadow on the wall.

Answer 1

To solve that question we must look for similar triangles. Lets do a picture.

Take triangle ABC. If we get a line parallel to its base, it divide its sides proportionally. We can write:

$\begin{gathered} \frac{60}{45}=\frac{length\text{ of shadow}}{\text{length of rod}} \\ \end{gathered}$

Then we get:

$\begin{gathered} \frac{60}{45}=\frac{length\text{ of shadow}}{12} \\ \\ 45\times length\text{ of shadow =60}\times12 \\ \\ \text{length of shadow=}\frac{60\times12}{45} \\ \\ \text{length of shadow=16}cm \end{gathered}$

The final answer is:

$\text{length of shadow =16}cm$