Unit 1 Vocabulary

5. points and lines that are in the same plane.
6. share a vertex and a side.
9. a unit of angle measure that is equal to 1/360 of a complete revolution; there are 360 degrees in a circle.
10. a point B is between two other points A and C if all three points are collinear and AB +BC =
12. angles that have the same degree of measurement.
13. any system of geometry in which the parallel postulate does not hold – hyperbolic and elliptic geometries.
18. points that do NOT lie on a single line.
21. the inside portion of the angle.
22. an angle that is greater than 90o and less than 180o.
24. the figure formed by two rays, called the sides of the angle, sharing a common endpoint, called the vertex of the angle.
25. the outside portion of the angle.
27. of an angle/ a line passing through the vertex of the angle that cuts it into two equal smaller angles.
28. can be combined with each other and with undefined terms to define more geometrical terms.

1. any angle less than 90 degrees.
2. all points between 2 given points.
3. lines that intersect at 90o angles; have negative reciprocal slopes.
4. distinct coplanar lines that never intersect; ALWAYS have the same slope.
7. angles angles that add up to 90 degrees.
8. the length of a straight line segment connecting 2 points.
11. the distance from one end to the other end of an object.
14. adjacent angles formed by intersecting lines; ALWAYS supplementary.
15. also known as the coordinate plane; contains the x and y axis.
16. the straight path connecting 2 points and extending beyong the points in both directions.
17. the elements that 2 or more sets have in common; indicated by the ‘cap’ symbol (upside down U).
19. lying or passing through the same line.
20. points that do NOT lie in a single plane.
23. the geometry of axioms, theorems, and two-column proofs.
26. a flat surface extending in all directions.