Work Step by Step
The triangles of the man and his shadow and the flagpole and its shadow are similar. This means that all of the sides are proportional. We will call x the side that we want to find (the height of the flagpole). Thus, we set up the equation: $x/6=17.5/3.5$. We multiply both sides of the equation by 6 to obtain that the height of the flagpole is 30 feet.