| __ | 1. | acute angle | | A. | angle greater than 90 degrees |
| __ | 2. | complementary angles | | B. | units used to measure angles |
| __ | 3. | congruent | | C. | the sum of their measures equal 90 degrees |
| __ | 4. | degrees | | D. | two lines in a plane that never intersect |
| __ | 5. | obtuse angle | | E. | the sum of their measures equal 180 degrees |
| __ | 6. | parallel lines | | F. | the point where the two rays of an angle meet |
| __ | 7. | perpendicular lines | | G. | angle less than 90 degrees |
| __ | 8. | right angle | | H. | lines that intersect at right angles |
| __ | 9. | supplementary angles | | I. | two angles with the same measure |
| __ | 10. | vertex | | J. | angle exactly 90 degrees |
| __ | 31. | Alternate Exterior Angles | | A. | Opposite sides of transversal, Inside parallel lines |
| __ | 32. | Alternate Interior Angles | | B. | Opposite sides of transversal, outside parallel lines |
| __ | 33. | Co-Exterior Angles | | C. | same side of transversal corresponding positions |
| __ | 34. | Co-interior Angles | | D. | Same side of transversal, outside parallel lines |
| __ | 35. | Complementary Key | | E. | Angle 1 = Angle 2 |
| __ | 36. | Corresponding Angles | | F. | opposite each other, congruent |
| __ | 37. | Supplementary key | | G. | angle 1 + angle 2 = 180 |
| __ | 38. | Triangle Key | | H. | Same side of transversal, inside parallel lines |
| __ | 39. | Vertical Angles | | I. | angle 1 + angle 2 = 90 |
| __ | 40. | Vertical Key | | J. | Angle 1 + angle 2 + angle 3 = 180 |