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Illustrative Mathematics
Area of a Trapezoid
Here is a straightforward example of how to apply the Pythagorean Theorem to find an unknown side-length of a trapezoid. Commentary gives additional information on proving that the inside of the trapezoid is a rectangle, but is...
Noyce Foundation
What's Your Angle?
Math can be a work of art! Reach your artistic pupils as they explore angle measures. A creative set of five problems of varying levels has young learners study interior and exterior angle measures of polygons. The introductory levels...
CK-12 Foundation
Ck 12: Area and Perimeter of Similar Polygons
[Free Registration/Login Required] Students move points to make diagonals in order to solve for area and perimeter of polygons. Click challenge me to answer practice questions.
Texas Instruments
Texas Instruments: Numb3 Rs: Regular Polygon Centroids
Based off of the hit television show NUMB3RS, this lesson shows students different ways to find centroids of regular polygons. The traditional way (using medians) is presented, as well as the triangulation method, the diagonals method,...