Question

Name a quadrilateral which is not a parallelogram?

Answer 1

one answer would be a trapezoid

Explanation:

A parallelogram must have sets of sides that are equal

A trapezoid has only one set of sides parallel and the length of the parallel sides are not equal so a trapezoid is not a parallelogram
( note a parallelogram would qualify as a trapezoid. )

Answer 2

Any quadrilateral which does NOT have its opposite sides being parallel is not a parallelogram.

Explanation:

An ordinary quadrilateral with no equal sides is not a parallelogram.

A kite has no parallel lines at all.

A trapezium and and an isosceles trapezium have one pair of opposite sides parallel.

A Concave quadrilateral or arrowhead does not have parallel sides.

The family of parallelograms includes:

parallelogram
rectangle
rhombus
square