Lines a and b are intersecting lines.[br]Congruent Angle Theorems:[br] Vertical Angles[br]Supplemental Angle Theorems:[br] Linear Pair Theorems (form straight line):[br] Adjacent Angles at Point E[br][br]Move one slider at a time, make observations Congruent Angles should be equal in size. The Supplemental Angles/Linear Pairs should add to be 180°.