Move point A to change the shape of the trapezoid. Then move the slider the extreme right to rotate the trapezoid.

1.) What kind of quadrilateral is formed when equals 180 degrees? Justify your answer. 2.) What is the relationship between the area of trapezoid ABCD and the area of the quadrilateral formed in 1? 3.) Using the quadrilateral formed in 1, find the area of the trapezoid. Hint: Use the , , and . More than 50 GeoGebra Tutorials at Math and Multimedia