[math]\angle[/math]ACD and [math]\angle[/math]BCD are adjacent angles that are [b][i]supplementary[/i][/b]. These angle pairs are sometimes called Linear Pair Angles or Straight Angles because they form a straight line. Notice that even when you move point D, the angles still add to 180[math]^\circ[/math].

[math]\angle[/math]JKM and [math]\angle[/math]LKM are adjacent angles that are [i][b]complementary[/b][/i]. Notice that even when you move point M, the angles still add to 90[math]^\circ[/math].

[math]\angle[/math]GIE and [math]\angle[/math]HIF, shown in blue, are a pair of Vertical Angles. [math]\angle[/math]GIF and [math]\angle[/math]HIE, shown in green, are also a pair of Vertical Angles. Notice that the vertical angles are the angles opposite of each other. Also notice that the vertical angles are congruent (the same). Look at one blue angle and one green angle. What do you notice about their relationship?