What properties are shared by all quadrilaterals?[br]How many ways can you think of to classify quadrilaterals base on different properties of their sides, interior angles, and diagonals?[br]How do these different classes of quadrilaterals relate to each other? Which are different ways to get to the same class, and which classes are subsets of other classes?[br]If you select some properties of a class of quadrilaterals, then what other properties do they automatically have?[br][br]This activity allows you to explore these questions and others related to quadrilaterals in Euclidean Geometry.[br][br]Click on the various check boxes to explore various classes of quadrilaterals and their properties. For each class a general dynamic quadrilateral is constructed. Manipulate the construction to see what additional properties the class has. Check the Properties check box to see a list of properties for each class. Now see if you can prove that the class has these properties. Proofs typically make use of the SAS, ASA, AAS, SSS, and HL congruence properties and/or the Z, C, or F properties of a transversal to parallel lines. [br] [br]