1. NAMING GEOMETRIC FIGURES

2. POINTS
A point names a location.
• A
Point A

3. PLANE
A plane is a perfectly flat surface that extends forever in all directions. P E
plane P, or plane DEF D F

4. LINES
A line is perfectly straight and extends forever in both directions. B C l
line l, or BC

5. LINE SEGMENTS
A segment, or line segment, is the part of a line between two points. H GH G

6. RAYS
A ray is a part of a line that starts at one point and extends forever in one direction. J KJ K

7. ANGLES A 1 C B
An angle () is formed by two rays with a common endpoint called the vertex (plural, vertices).

8. A right angle measures 90°.
An acute angle measures less than 90°.
An obtuse angle measures greater than 90° and less than 180°.

9. The measures of angles that fit together to form a straight line, such as FKG, GKH, and HKJ, add to 180°. F K J G H

10. Complementary angles have measures that add to 90°.
Supplementary angles have measures that add to 180°.

11. INTERSECTING Lines
2 or more lines that meet at a given point
Parallel Lines
lines in a plane that do not intersect

12. Perpendicular Lines
lines that intersect to form right angles

13. Intersecting lines form two pairs of vertical angles
Intersecting lines form two pairs of vertical angles. Vertical angles are always congruent.

14. Angles in the same plane that have a common vertex and common side are adjacent angles.

15. In the figure, 1 and 3 are vertical angles, and 2 and 4 are vertical angles.
A. If m1 = 37°, find m 3.

16. A. Name 4 points in the figure.
B. Name a line in the figure.
C. Name a plane in the figure.
D. Name four segments in the figure.
E. Name four rays in the figure.