MoMath friend Dave Masunaga from Iolani School in Honolulu wows a group with some surprising geometry at the National Gallery of Art in Washington, D.C.
@teacherteachHer @robertkaplinsky I believe it is a debated issue. However , the inclusive definition (parallelogram is a special trapezoid) is used in Calculus.
Someone put out a survey about this topic not that long ago. Can’t remember who.