Similar triangles: proportions
The Shadow
A flagpole casts a 36-foot shadow while a 5-foot person casts 4 feet. A three-minute film on why the sun turns the two into the same triangle at two sizes, and how one proportion gives the pole's height.
This browser has 3D graphics turned off, so the set cannot be drawn. The math and the narration still play.
The problem
At a certain time of day, a flagpole casts a shadow 36 feet long. At the same time, a person 5 feet tall standing nearby casts a shadow 4 feet long. How tall is the flagpole?
45 feet
