Google Classroom
GeoGebraGeoGebra Classroom

Is a Trapezoid a Parallelogram?

Quadrilateral ABCD starts out as a trapezoid with AB||CD. Drag point D left and right keeping AB||CD.

Under the classic definition of a trapezoid (also called the exclusive definition), there is one place you could land D that would suddenly make ABCD NOT a trapezoid anymore. Where is that location? What do you think about the fact that this shape is suddenly no longer a trapezoid?