On Tue, 11 Nov 1997, Eileen M. Klimick Schoaff wrote:
> I have encountered two different definitions of trapezoids in textbooks. > > 1. Trapezoids are convex quadrilaterals with exactly two parallel sides. > > 2. Trapezoids are convex quadrilaterals with two parallel sides.
The inclusive definition 2 is to be preferred for reasons mentioned earlier.
Michael de Villiers
> > Definition #1 eliminates parallelograms as being a subset of trapezoids. > Definition #2 would include parallelograms and could be restated as: > Trapezoids are convex quadrilaterals having as least two parallel sides. > > In New York State, we use definitions #1, but encountered #2 in an NCTM > Addendum book we were reviewing. Talk about controversy!!! > > Eileen Schoaff > Buffalo State College > >