1. Geometry
Chapter 1
Sections 2-3

2. Point
-A precise location or place on a plane. Usually represented by a dot
-A, B, and C are points in the diagram below

3. Line
-A straight path through two points, that goes on endlessly in both directions
-A line does NOT have a set measure
-The line below is notated as
The arrows in the diagram and in the notation show that the line goes on endlessly in both directions.

4. Line Segment -A straight path that connects two end points.
-Segments have a set measure.
-The segment below is notated as

5. Ray
-A straight path that starts at an endpoint and goes endlessly through another point.
-A rays does NOT have a set measure.
-The ray below is notated as

6. Collinear Points that lie in the same line P, Q, and R are collinear
X, Y, and Z are non-collinear

7. Coplanar
Points, lines, rays, or segments that lie in the same plane.

8. Angle
-The amount of turn between two straight lines that have a common end point (the vertex)
-Angle are measured in degrees
-The angle in the diagram can be notated as B, ABC, or CBA
-The vertex must be listed in the middle when naming angles.

9. Acute Angle -An angle with a measure of less than 90°
-The angle in the diagram could be notated as E, FED, or DEF

10. Obtuse Angle
-An angle with a measure of more than 90° and less than 180°
-The angle in the diagram could be notated as B, ABC, or CBA

11. Right Angle
-An angle with a measure of EXACTLY 90°
-The angle in the diagram could be notated as K, JKL, or LKJ

12. Straight Angle -An angle with a measure of EXACTLY 180°
-The angle in the diagram could be notated as Q, PQR, or RQP

13. Segment Addition Postulate
-If point B lies along segment AC, then AB+BC=AC
If I walk 2 feet and then I walk 6 feet, how many feet did I walk total? That is the same thing that this postulate says.

14. Segment Addition Postulate Example
Solve for the length of segment DE

15. Angle Addition Postulate
If ray SQ is inside angle PQR, then RQS + SQR = PQR
If I open a fan 15 degrees and then open it another 25 degrees, how far have I opened it total? That is the same idea that this postulate represents.

16. Angle Addition Postulate Example
If we know that ABD=93°.
Solve for x.