2. Lines and Angles

3. Ray

4. Congruent Equal in size and shape.

5. Degrees The unit used to measure angles. 70

6. Line Segment A part of a line that has two endpoints.

7. Line A series of points that go endlessly in both directions.

8. Vertex The point at which two rays join together to form an angle.

9. Obtuse Angle An angle that measures more than 90 degrees and is less than 180 degrees.

10. Acute Angle An angle that measures less than 90 degrees. J L O

11. Right Angle An angle that measures 90 degrees.

12. Straight Angle An angle that measures 180 degrees. (a.k.a. straight line)

13. Parallel Lines Two lines that are equal distance apart and will never intersect.

14. Perpendicular Lines Two lines that intersect to form two right angles.

15. Opposite or Vertical Angles Angles that are opposite one another are equal in measure. A B T J C

16. Adjacent Angles Angles that are next to each other and share a common side. A B