Consider what you know about parallelograms.
Which of the following quadrilaterals are not parallelograms? Select all that apply.
In part (a), we found that the quadrilateral pictured below is not a parallelogram. What type of quadrilateral is it?
Illustrate a statement about a geometric property by demonstrating the statement with multiple examples, or deny the statement on the basis of a counter-example, with or without the use of dynamic geometry software