Watch Quadrilaterals

Quadrilateral basics are introduced with an analysis of the post and lintel construction at Stonehenge and evident in most house construction. An analysis of the quadrilaterals in Frank Lloyd Wright's "Falling Waters" provides an additional example of how quadrilaterals and a balance of geometric shapes are used to suit a building to its surroundings. The TI-Nspire is used to demonstrate that quadrilaterals can be made from congruent triangles, with the greatest area being provided by right-angle congruent triangles. After comparisons of the areas of rectangles and parallelograms, an analysis of Falling Water's cantilevered balcony provides a thorough understanding of torque and center of gravity in rectangular constructions. In the final section, the geometry of the Puerta de Europe towers in Madrid is thoroughly analyzed on the TI-Nspire. The analysis explains how the center of gravity of the towers is affected by the angle of tilt of the parallelogram and how a trapezoid is formed in the space between the towers.

Quadrilaterals is a 2007 special interest movie with a runtime of 23 minutes.