Two Lines Cut by a Transversal

Drag the BLUE points on the figure to change the position of the lines. (Note: You cannot drag the black points). Click on the button in the upper right to "make line CD parallel to AB." Click on the "Reset" button to return to the previous configuration. This material is based upon work supported by the National Science Foundation (#1453493, PI: Michelle Cirillo). For more information about the project visit:
What pattern do you notice in the angles?