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Dr. Frank's Math Minute »» Similar Triangles and the St. Louis Arch

Similar Triangles and the St. Louis Arch

2500 years ago, Thales used Geometry to find the height of the Egyptian Pyramids. Today, Dr. Frank uses Similar methods to find height of the St. Louis Arch!

It is believed that Thales of Miletus (624 to 547 BC) was the first person to use similar triangles to find the height of a very tall object. Thales noted that at a particular time of day, the height of an object and the length of its shadow were the same. He then used this observation to calculate the height of the Egyptian pyramids. Later, he brought this knowledge back to Greece and his observations are considered to be a forerunner of the technique of using similar triangles to solve such problems.

Click to download the accompanying Handout and Worksheet ... Coming Soon!

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