Several types of quadrilaterals and their
diagonals have been constructed in the sketch below Use the buttons
to make figures appear. Figures will overlap, use the hide button to hide
an obstructing figure.
(Note: The sketch below requires
a Javaenabled browser. You can access the
real sketch here and use The Geometer's Sketchpad to open it. Sketchpad
is available from Key Curriculum Press).




Diagonals form congruent triangles? How Many if so? 
Quadrilateral         
Parallelogram         
Rectangle         
Square         
Rhombus         
Trapezoid         
After completing the activities above you should have a fair idea of how these quadrilaterals compare with one another.