4 lines are shown. A line with points E, C, D is horizontal. Another line intersects the line at point C and extends up and to the right to point A. Another line intersects the line at point C and goes down and to the right to point B. Another line connects to all 3 lines. It goes from point A, to point D, to point B. Use the diagram to identify the special angle pairs. ADC and BDC are . A pair of complementary angles is angles .