Parallel Lines and Transformations in a Parallelogram

This lab uses transformations to show that angles are congruent in a parallelogram.

1) Using transformations, predict what angle is congruent to <ACB. 2) Click “Show Reflection of <ACB in BC.” Is <ACB <DCB? 3) Uncheck “Show Reflection of <ACB in BC.” Predict what transformation(s) map <ACB onto <DBC. 4) Click on “Show Translation” and “Show Rotation.” 5) Write a paragraph proof, using transformations proving that <ACB is congruent to <DBC. 6) <ACB and <DBC are alternate interior angles. Which parallel lines form these angles? Which line is the transversal? 7) Drag points A, C and B. Is <ACB is congruent to <DBC always true? Why or why not?