precalculus
posted by Kelsey on .
A man is walking away from a lamppost with a light source h = 6 m above the ground. The man is m = 1.5 m tall. How long is the man's shadow when he is d = 11 m from the lamppost? (Hint: Use similar triangles.)

Let the man's shadow length be x.
Draw the figure showing how the shadow is cast.
Similar triangles should tell you that
6/(11 + x) = 1.5/x
Solve for x
6x = 33/2 + 3x/2
9x/2 = 33/2
x = 33/9 = 11/3 = 3.667 m