1. Angle Relationships
Geometry 1.5

2. Adjacent Angles
Two angles which share a vertex and a side, and nothing else.

3. Complementary Angles
Two angles which add up to 90°; they are both acute.

4. Supplementary Angles
Two angles which add up to 180°; either they are both right angles, or one is acute and the other is obtuse.

5. Linear Pair
Two adjacent supplementary angles: They form a straight angle (line).

6. Linear Pair
Two adjacent supplementary angles: They form a straight angle (line).

7. Linear Pair
Two adjacent supplementary angles: They form a straight angle (line).

8. Linear Pair
Two adjacent supplementary angles: They form a straight angle (line).

9. Vertical Angles
Two angles on opposite sides of intersecting lines; they are always congruent.

10. Vertical Angles
Two angles on opposite sides of intersecting lines; they are always congruent.