Latest News


Special Promotion on Whaley Three-Line Gradebook and The First Days of School Book

Back-to-School Promotion on these two useful teacher resources.

Read More »»

Ground-breaking Manipulative Introduced!

Fraction addition, subtraction, division, and multiplication clearly demonstrated!

Read More »»

Save $$: Have Dr. Wang come to your school.

Best conference speaker at your school !

Read More »»

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!



If you enjoyed this Dr. Frank's Math Minute, you may also be interested in:
Group Theory with Fruits